I did lockpick first so i could get the Gobi Campaign Scout Rifle which was a good decision.

...As many as possible.

Primarily, Repair, Speech, and Energy Weapons.

Secondary I'll take Guns, Survival, Lock-pick, Science.

I start off with 10 In usually, I make sure by level 35 I have a basic Negotiator/Well Rounded tank to run around in.

aka, Commander Shepard.

.....most of them

Explosives, Guns, Melee, Repair, and Science. Speech, Lockpick, and Medicine can get to 100 with items.