I try to help when possible 
Well the standard rules of stats go along these lines (yep you need to know this to see what imsaying
)
its not set in stone but genreally because of how statistics are set up, you would see it as ...
Hackers most likely to beat Spy
Spy most likely to beat Gunmen
Gunmen most likely to beat Martial Arts
Martial Arts most likelt to beat Hackers
and repeat.
Now in the NPC enviroement, which concerns you most you need to know they mostly are guns. Now generally you can pick any loadout against NPC's and from a low lvl MA/Guns are always best. You are fine to go and use the loadout you prefer, but always remember that basic rule above. If your good with your load, then you can learn to counter any loadouts.
So the issue at hand its when against NPC with Guns. Firstly always have the hyper-dodge on, and now in your situation you need to see which moves you want to use, when I say use kung fu, use that as your basic attack style, then as you prefer to use a high damage move that requires a state, then have power tactics selected, so you have the accuracy of using kung fu and the power tactic, once a person is staggered then you will be able to use the karate attack anyway.
If you find your attacking the NPC with ease, you can then switch to karate base attacks to increase your damage output.
All trees have good points to them, kung fu has the best for accuracy so you hit more, but your damage isnt as good as using a karate style, karate is likely to hit less but each hit that does go through will do more damage, so you see the trade off you are left with.
As for tactics, be ready to change at any given moment, if your using red and not hitting, switch to blue or green, if you need to regen IS/health switch to block tactics, that gives 50% bonus to defense.
as for black /white rule, far from it, this is the matrix and there are no rules 
What I would say is try a few variations until youare comfortable with your own tactics.
Also remember while you might use accuracy/defense buffed clothes, when facing npc's try to have as much in ballistic resistance also, defense is good, but each time you get hit reduce the amount of damage they do, you'll find this can help you last long enough to get your own state requirements and land high damage moves on the NPC.