Before you do anything else, you absolutly must have:
Iron Will [your Will save will be envying the barbarian's by the time you're done multiclassing]
Periapt of Wisdom [see reason above]
Cloak of Resistance [see a pattern emerging?]
An easy source of Protection from Evil [for its Charm and Compulsion-defeating virtues]
---------
After that, it's no worries. What I do recommend is Quickdraw, Weapon Focus, Weapon Specialization, and the TWF chain. You will have ~5d6 in Sneak attack dice, and TWF will help you get some more shots in. Quickdraw is a necessity if you're going throw-guy. WFoc and WSpec will apply to all of your attacks and damage dice, so they should be a pick-up.
So my recommended feats are...
Iron Will (You get no choice here. Must take
)
Weapon Focus: Dagger
Weapon Specialization: Dagger
Two Weapon Fighting
Improved Two Weapon Fighting
Greater Two Weapon Fighting (Depending on BAB)
Quickdraw
Weapon Finesse (if your Dex is greater than your Str... which it will likely be if you go the TWF route.)
If you're a Fighter4/Rogue11, those will take up 8 of your 10 available feats. You will lay a hurting down if you have a flanking buddy, and you won't be useless from range (Point Blank Shot and Far Shot can round this out to help your ranged effectiveness). You will not, however, be able to claim any swanky multiclass combo, so all the coolness will have to come from how you play your character.
And I recommned the Rogue's Crippling Strike special ability, the one that reduces the target's STR by 2 if you Sneak attack. With you flanking, that could leave someone paralyzed fairly quickly.
Or Slippery Mind. Either way.
Iron Will [your Will save will be envying the barbarian's by the time you're done multiclassing]
Periapt of Wisdom [see reason above]
Cloak of Resistance [see a pattern emerging?]
An easy source of Protection from Evil [for its Charm and Compulsion-defeating virtues]
---------
After that, it's no worries. What I do recommend is Quickdraw, Weapon Focus, Weapon Specialization, and the TWF chain. You will have ~5d6 in Sneak attack dice, and TWF will help you get some more shots in. Quickdraw is a necessity if you're going throw-guy. WFoc and WSpec will apply to all of your attacks and damage dice, so they should be a pick-up.
So my recommended feats are...
Iron Will (You get no choice here. Must take

Weapon Focus: Dagger
Weapon Specialization: Dagger
Two Weapon Fighting
Improved Two Weapon Fighting
Greater Two Weapon Fighting (Depending on BAB)
Quickdraw
Weapon Finesse (if your Dex is greater than your Str... which it will likely be if you go the TWF route.)
If you're a Fighter4/Rogue11, those will take up 8 of your 10 available feats. You will lay a hurting down if you have a flanking buddy, and you won't be useless from range (Point Blank Shot and Far Shot can round this out to help your ranged effectiveness). You will not, however, be able to claim any swanky multiclass combo, so all the coolness will have to come from how you play your character.

And I recommned the Rogue's Crippling Strike special ability, the one that reduces the target's STR by 2 if you Sneak attack. With you flanking, that could leave someone paralyzed fairly quickly.
Or Slippery Mind. Either way.