I want to make a freelance assassin character that is fun to play as and I want to make sure that this doesn't happen: bliviongate:
So any tips on how to get started on that character after getting the hell out of the tutorial?

Hm. Maybe do the Arena, unless it screws up your RP. Loot some dungeons, kill some guy. Get into the DB. Do the neutral quests but never do people favours.

If you don't want the oblivion gates, don't go to Kvatch.

Freelance assassin, find a bandit cave or necromancer pit, pick a bandit to be the "hit", think of a reason or person who wants them dead..
Don't kill anyone else there, unless spotted, as you've not been contracted for them to die, report back to your payer or "contractor".
Repeat as many times as you like, think of back stories, plant evidence, or find some, see what ways you can kill them.. so on.

If you don't want to worry about leveling perfectly get an attribute mod. Join the DB for sure obviously. Might wanna kill people that piss you off if you're a freelancer haha.

I know this might be a tad on the sick side, but...

Whenever you're in town, roll a 6 sided die. The X -th NPC you encounter is your mark. Find a way to kill him. If he ends up being a guard, you got yourself a long-term goal.

RP wise, I like to approach it as if my character looks through his scrolls for a list of people that needs killing... so you might want to avoid rolling your die in public.

My main character has a personal vendetta against beggars. Kill them all. It's trickier than it sounds.

And to make sure the gates to hell don't start popping up everywhere, drop the Emperors bling over at Jauffre's pad, and then jet it. B)

Related to what Madocmayhem suggested-- maybe your character has accepted a contract to, ah, "retire" every necromancer in the country by-- who? Depends on your character concept! A necromantic organization in another country who intends to move in and establish themselves? A religious cult? Someone with money and a grudge? Pay yourself (via player.additem) a bounty for every "head" you take, with a bonus for every fort or ruin you clear out.

Or replace "necromancer" with "bandit," or whatever other group you think might be fun.

Can you get rid of every Count/Countess? or are they unkillable...?

How about you target a specific race? maybe kill of all but 1 kind of merchant. Even something that has to do with the small villages could be interesting.

Oooh. That sounds like it could actually be a lot of fun-- sort of like a horror movie in the making, with the PC as a sort of angel of death. Like one day, a courier or someone stops by a small village and finds everyone dead... and then reports begin to trickle in about the same thing happening all over Cyrodiil....

rp'ing an assassin with a specific goal in mind is lotsa fun.

mine has some personal history with the empire (as the 'establishment', central power). so shis advancing in all guilds, including blades, and at some point (i dont know when) i will try to have her somehow betray the imperial forces and block martin's crowning or whatever.

i dont know if i will have terminate all the most important guild members, most of them, etc...