Feycraft is in the DMGII. I would suggest going ahead and writing out a sample build including feats and skills and see where that gets you. Then you can focus in on the things that you really want to do, versus things that might be neat. Factotums as a whole can do anything; but each individual has to pick a few things to be good at.
Concept: Assassination
Skills: Hide, Bluff, Diplomacy, Escape Artist, Spot, Listen, Search, Disguise, Iaijutsu Focus, and Move Silently. Those are the ones I'd want to max, or at least have a +20 whenever I roll.
Feats: Not really sure what feats would aid my character concept besides Poison Use, Exotic Weapon Focus, and Font of Inspiration (which can be taken multiple times). Any suggestions?
Level 1: Poison Use, Exotic Weapon Focus.
Level 3: FoI
Level 6 and on???