From other games, I have been used to collect everything available in order to sell or keep it, but while playing Morrowind, I had to modify that strategy so I only kept things valuable enough.
But in Oblivion my collecters mid has been even more challenged, since the levelled loot makes everything I find valuable enough to keep but way too heavy to carry even for my crusader. I just radied a vampire cave, where I found my first elven warhammer and glass battleaxe, where the battleaxe is probably the best unenchanted weapon I have found yet, but I had to leave them both behind, because I could not carry 146pound extra.
I have thought about getting a feather or fortify strenght spell just to be able to get some extra loot

So do other people pickup everything interesting or are you leaving all the treasures behind at some stage?
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I'll take anything with a value-to-weight ratio of 10:1 or better. Everything else stays behind.

EDIT: Ratio increases with level. 10:1 is quite valuable early on but nearly worthless at higher levels.

Yea, it all depends on the value-to-weight ratio, as Alleystria said.

I used to loot everything of value with my first couple characters. So this means several weapons, sometimes several sets of armor, and enchanted items, etc. I'd carry as much as I could until my character literally couldn't move anymore.

Later on (starting with Renee Gade II, actually) I decided to limit this to what's more realistically possible. I got a system. My newer chars usually walk into a dungeon with all the regular weapons & armor (iron, leather, steel, etc) then whatever they happen to find in the dungeon, they'll replace their cheaper piece. So if she finds a shield that's enchanted with 7% magic resistance, she'll drop her regular iron shield in replacement.

Some pieces even get left behind, depending on what my character can carry realistically! Some pieces get sold. And some get stored in a house.

My characters usally have some form of feather, and use it often..
Recently I have been using a modded alteration spell that at the cost of a flawless diamond allows acess to a "bag of holding".
So early on I take little in the way of loot, but at later levels I can carry more, which is handy with no fewer FT's.

Then when I have a house, weapons, spells I limit myself more to just collecting gems, pelts, potions, ingredients, rare items and items to make the house look pretty.

I'll second that value/weight ratio point, and especially how it increases as you progress.

Early in the game you need to pay for more things so you grab anything that has a value at all, and sell it to buy a decent set of armor or a weapon. Once you can repair enchanted items and soul-trap for recharges, you don't need to spend so much on those services, but you'd like a house to sleep in, so your gold needs are still there. You can now consider keeping the enchanted items instead of selling them, so you sell the ones that don't fit your character's style, but you leave the cheap unenchanted stuff in the dungeons. Eventually you bought all the houses, the gold you find covers all the purchases (or fines) you might make, and you don't need to sell anything, so the ratio becomes infinite! Now it's just stuff to decorate with, and you may even pick up items with no value at all, because they'd look good on a shelf somewhere.

Some of my high-level characters get quirky and collect forks in memory of Big-head, or fill their houses with planters of flowers.

I loot like crazy, I used to do a ratio on what to carry but now I just carry up to my weight and whats worth keeping money wise when I loot a dungeon.

I used to loot everything.... Now I will only take armor if it completes one of my sets. I look for arrows, nice bows, unique jewelery and nice blades, especially daedric short swords.

I leave my character's strength at base. It's an RP thing as she is a physically weak no-melee mystic archer.

She quickly learns how to make money by making potions and enchanting cheap jewelry to sell.

She this is about all she picks up:

Alchemy ingredients
Gold coins
Arrows
Rings, amulets and soul gems - to toss in the altar, enchant, then sell.
Maybe lockpicks since they weigh 0.

Even her tiny inventory is not full when she comes out of a dungeon.

I sell all valuable equipment at the beginning, just going back and forth between the dungeon and the city (usually 4/5 trips). Now that I have a bit of money I only take daedric armors for enchanting.

:gun: :rock: i take small weapons and sell them :woot:

My character used to loot everything until he got tired of casting feather spells and realized he didn't really need the money anymore and he has grown to respect his foes more. Now he only loots highly valuable items or potions and he always loots from his hated foes inside the gates of Oblivion!

In every new game I′m just like you, I collect everything I can possibly carry. Even so in Oblivion and Morrowind. However after almost four years of playing I rarely pick up anything at all, unless it′s a very rare enchanted item such as Mundane Ring

Yup. I usually take potions and scrolls though since they barely weigh anything and can be useful most of the time.

I think it was when I found myself carrying around duplicates of the Mundane Ring, Amulet of Axes, Necklace of Swords, Sorceror's Ring and a few others - all of them priced at way more than you can ever sell them for - that I decided it wasn't making sense, and stopped picking up anything I wasn't going to use.

Display case those haha.

It depends on the character. Some of my characters aren't interested in looting at all and don't do it. Other characters loot. Some characters are only interested in looting certain items. They aren't interested in other items. When you roleplay, it's nearly impossible to make universal rules that apply to every character.

For my characters, it depends first on what sort of personality they have and second on where they are in the game. Most of them loot just about everything at the beginning of the game, when money's hard to come by, but later they tend to get more selective, since money's not such a pressing concern any more.

And the ones who do collect a lot of loot usually not only know Ease Burden, but have it hotkeyed. And they learn early on how to make feather potions.

Just like most others I would loot everything in site

later on I would replace armor with better armor that I might find then sell the old...same with weapons and any other equips

With enough feather spells and fortify strength spells you can easily carry all of Fort Blueblood back to a merchant to make gold off of (that is, all of the equipment looted from the dead marauders in there, quite obviously you can't Yoda the fort and bring it back to IC to auction off). I did that in my new player days of the game as a means to make cash.

On Oblivion, my level 16 Dunmer "Quest and fight character" only carries the things he needs, so my encumbrance is 200/545 (With a couple of feather enchantments). When I reach maximum encumbrance, I ride my pimpin' Shadowmere to Bravil, and leave all the valuable stuff (1200 and over) in my pimpin' house, while all the others go to sale in the pimpin' Fair Deal. Now I have a lovely 200/545 again, and so the cycle continues. I always loot everything of a value 20 or above. Especially potions and poisons, there is a ton of them everywhere...

If you follow this technique (On GotY PS3 Oblivion edition), you can be sure to have at least 50,000 by level 15 (I don't know if that's a lot for you guys, but it is for me xD).

I take everything that has good value and use tons of feather and strength potions, spells, and enchantments on my armor. This is especially the case in caves and forts and stuff because I'm not a fan of them and if I take the time to head into a dungeon or cave I'm not about to leave stuff behind that I could sell for some good money.

I take weapons and armor that I can sell for decent money (relative to game progress; at level 37 currently and I usually take all weapons above silver and the top three tiers of light and heavy armor), jewelry, spell scrolls, soul gems, potions and other light useful stuff. A lot of potions I'd leave behind, but once I take the time to open the chest/drawer/etc I figure I might as well "take all" and sell useless stuff later. I leave behind all trash (shears, calipers, etc.) as well as all silverware and decoration stuff, un-enchanted clothing, crap weapons and armor, most books, alchemical ingredients that don't yield what I use, and I rarely check crates/barrels/etc, only chests.

In the beginning, yes, to build Mercantile and gold reserves (for Arcane University custom spells and/or enchants). Once she has clothing and accessories with Fortify Strength IV (greater soul gem) she tends to not need to worry about taking everything. However, her strength begins so low (25-30 depending on which custom race I am playing) just simply equipment can overload her quickly. That's something I've learned about trying to play an archer-type character... even bow and arrows wind up being an issue for my characters unless I do something about their strength. Same with potions... having a decent supply on hand can be a problem for her.

Lately, I prefer leaving strength alone (aside from enchanted clothes to boost it as I said) and using only spells, at least until around level 20. Of course, by that time, she's pretty much invincible, anyway, and gold reserves are no longer an issue (high Mercantile through development and spells). I usually can freely choose what to do and how to play without worrying about consequences. I always leave high level strength for last in development, though, which means I never have really maxed it out unless I finally get characters to level 52. I think the highest I ever took strength is maybe about 60 (from 25-30). I just don't need it.

I gave up carrying out heavy armor a long, long time ago...

I try to loot 1 of everything because I'm a major packrat.
Not always that I loot everything but if I am normally I'll kill something and drag it to the entrance of wherever I'm raiding. Then drag another corpse on the other side of the door to that spot this second corpse is where I tend to move everything till I'm done.
If I make a corpse that is easy to drag along I will bring it around with me, but once it's all on the second corpse on the other side of the door from the first I just grab it all go through the door store what I can't fast travel with on the first corpse and put it all at home.
If I couldn't take it all with me I change into clothes or anything with feather or strength enchantments and fast travel back for more. Feather and strength enchantments help a lot especially castable spells.
After I have stuff neatly put away I decide what I have excess of in my collections of general munitions if it doesn't get stored as a trophy I sell it off later when I need septims which usually takes a few trips.

I use to drop stuff on the ground but I get a glitch where stuff falls into the ground and its usually easier to throw it all on a corpse and drag it around as a container.

I honestly pity anyone that tries looting with a fresh altmer character 30 strength is the pits. I gave up on mine around level 5 or 6 when I dropped my pay day stack of 8 iron curiass' through the ground.