Having played a TM for a while now, I'll say there is one main thing any TM should have:
A team that supports you.
Yeah, that may sound silly, but there it is. To build a strong-in-the-Matrix TM, you're going to be lacking on a lot of other skills, like, oh, Dodge, and you need the other players at your table to know that until you get the karma to advance, they need to watch out for you. In exchange, you'll do wonderful feats like give the gun-bunny an extra 4 or 5 dice for their firearms tests and run tac-nets that are unhackable (from mundane hackers).
Basic skills you'll need:
Software (for threading)
Computer
Data Browse (unless you have a sprite who does it, but I'd never rely totally on someone else, you know what I mean?)
Hardware
(might as well get the group)
Cracking Group (Hacking, Electronic Warfare, Cybercombat)
Compiling
Registering
(decompiling can be handled with a strong enough Attack CF)
So... there's 9 skills you need.
I'd also highly suggest starting with your Resonance at 6, and see if you can get some double-play from your fading attribute (ie, technoshaman + elf for a high Charisma, then you can double as a face/negotiator, especially after a bit of karma and some empathy CFs).
If you look there are some good sample builds posted around here.