with OB crazy leveling scale, im so used being able to handle any quest with the difficulty that it was ment for. I know Morrowind does not scale to the player but i want to start the exspations as soon as possible.
so here is my questions.
What level should i reach before i start those quest lines or enter those regions?
PLEASE QUOTE ME IN YOUR A# TO MY Q#

Most people suggest around Level 20 for Tribunal, and around Level 25 for Bloodmoon.
This is based on quotes from Bethesda when they released the expansions.

Depending on how good your gear is, you might find it too easy or too hard at these levels.
But they do both get progressively harder as you play their respective Main Quests. (especially Bloodmoon)

Aye, Bloodmoon indeed gets very difficult towards the end regardless of your level. You may also find the end of Tribunal difficult depending on the type of character you are.

One possibility, if you don't want to spend the time leveling up in the main game, is to knock the difficultly slider waaaaay down. Or, if on PC, use console commands to increase your characters skills and attributes to where they'd be if you were at a higher level.

Not so much an issue of level as it is equipment and playing skill, resourcefulness. Without going into too much detail, Tribunal takes place in Mournhold, which is a wealthy city, and as such is full of places to replenish ones supplies, making that particular part of completing the respective MQ pretty much a non-issue. Bloodmoon is on the island of Solstheim, which is, pardon the pun, the polar opposite. For the most part there's nothing but you, the snow, and the monsters.

So adapting ones approach to either one is important. With Tribunal you can afford to not carry so much around, which enables you to carry more of your more heavy-hitting enchanted items/weapons, that you might normally cut down on the number of. For example, I used to find it handy to enchant several Glass Longswords (they're light, and not hard to come by) with Fire, Frost, Shock, Poison, Damage, Drain, Absorb, Paralyze, whatever would work best against certain enemies, and have them all with me when "going to war", so to speak. And you'll usually know when you've got a fight coming in Tribunal. Then again, that may be too hardcoe, but you get the idea.

With Bloodmoon, conservation of encumbrance is essential. Unless you like leaving piles of stuff everywhere. You do not want to get stuck being over-encumbered or even weighed down just a little too much when the monsters come calling on Solstheim. Of course, there's always levitation, which is the best weapon of all on that island. In fact, yes, invest heavily in levitation. Casting spells, using enchanted items, drinking potions, whatever. Just get used to climbing to the heavens. You'll thank yourself.

But, you did ask what level, so if I had to pick one, I'd say... 30. For Tribunal. Bloodmoon probably 40.