It seems some skills that are useless without 3 CPs

I'm surprised to hear this. I've played several thief-ish characters and always had a lot of fun. Granted, I don't think I ever completed the entire game with any of them. Honestly, it just isn't fun shooting your way through the BMC as a thief. Generally my thief characters came to an end after I'd visited all of the major cities.

I think only ever went for the magickal route once. Other than that I've always found tech to be a bit better. Some points in mechanical can go a long way. Bear traps are useful for getting backstabs and as a way to immobilize bothersome guards.

It might even be worth it to put points into explosives for stun grenades, or even to go further get points in chemistry. Knockout gas or paralysis grenades might be useful in a pinch. Of-course that would be a pretty big investment.

 

I robbed the bank with a dwarf that had 0 skill in prowl. First I agreed to Ben to rob the bank, so that he gave me the code to the safe. Then I did the Benson Gang quest with the Doc (where 3 bandits try to rob the bank in bright daylight). During that quest one of the banks guards is always killed. With their old revolvers the bandits are nearly harmless and after they are dead and the Doc has handed out my quest reward and the left for his office again, I return to the bank on the same day enter the tresor room, open the safe, take the 500 gold (which is a joke - the shopkeepers keep the quadruple amount of that in their shops) and the quest is done.

Edit: Or rather the quest is not done... After taking the meager 500 gold from the bank I wondered why I should simply hand over half of that to Ben. Kill him perhaps? Then I remembered that I had had the option to rat him out to the Constable and the Doc just after accepting his "rob bank"quest but before actually doing it- and that option was still there.

Now I get the safe-code from Ben, accepted to rob the bank and split half, simply walked into the safe room using the key that I pickpocketed from the clerk in the bank and taking the 500 gp using the codes. No negative attitude modifier or fulfilled quest yet - the game expects me to hand over the 500 to Ben to strike me with that... So - instead of going to Ben, and to lose 250 gold to get his quest completed and receive the "quest reward" of negative attitude modifier, I walk over to Doc and tell him that Ben wants to rob the bank - and Ben vanishes and his quest is botched...

No negative attitude modifier from robbing the bank, keeping the full 500 gold without having to share with Ben AND being hero of the town for slightly helping to stop the Benson Gang (my bankrobbing rivals)