In this part of the guide, I am going to talk about the skills and their utility, talking about EACH AND EVERY ability tree.

IMPORTANT NOTE: I am going to talk about each individual skill, therefore, I am not doing a specific bulid, but a global explanation about every "stealthy" ability. So I RECOMMEND YOU TO MAKE YOUR OWN BUILD according to my suggestions and the equipment you use.
Let's start:
GHOST TREE (IN MY OPINION, THE MOST IMPORTANT TREE):
*SHINOBI SUBTREE: This subtree allows you to improve your ecm's. which is quite important in the contracts:
When you improve this subtree, you are able to:
-OPEN ELECTRONIC DOORS with ecm's, where you might found parts of a mision (for example servers, in big oil job) or security rooms.
-Lock-pick safes
-Mark civilians when you stay still,
I RECOMMEND TO IMPROVE EVERYTHING TO ACE IN THIS TREE, but the "cleaner" AS skill, because you won't need to carry bodybags unless you use "jack of all trades"; a skill in the Technician-Engineer subtree.

*ARTFUL DODGER: I only recommend to use the first three skills (Duck and cover, Parkour and Inner pockets) without ACE, because it will increase your velocity and decrease your concealment.
*SILENT KILLER: As the previous one, I recommend to only use the first three skills, with exception that "Optical Illusions and The Professional" being on ACE

MASTERMIND TREE
In this tree, I only recommend to use the mastermind subtree, with "Forced Friendship and Confident" skills on basic.

ENFORCER TREE:
In this tree, I only recommend to use the tank subtree, with "Resilience and Transportes" skills on basic, just to throw your bags further.
//Ammo specialist: Scavenger basic, Portable saw and Extra lead on Ace, if you want to have the saw.//

TECHNICIAN TREE:ENGINEER SUBTREE: //YOU CAN USE THIS IF YOU WANT TO CARRY TWO EQUIPMENTS, LIKE 2 ECM'S AND 1 AMMO, OR 1 BODYBAG CASE, OR WHATEVER YOU WANT
Third law and Jack of All Trades on ace.
Breacher Subtree: HARDWARE EXPERT, drill sawgeant and kickstarer on ace.
IF YOU WANT, you can use More Firepower and Body Expertise on ace if you want to have deploying mines.
Oppressor Subtree: Steady grip on basic, just to improve your weapon.

FUGITIVE TREE:
I recommend to use only the Gunslinger Subtree, as It will improve drastically you secondary weapon.
I reccomend EQUILIBRIUM, GUN NUT AND ONE HANDED TALENT .

YOUR SECONDARY WEAPON:
I recommend any SILENCED PISTOL, with all the Skills I recommended, any pistol will be really good to play on stealth.
I personally use the akimbo single pistol.

REMEMBER, USE SKILLS THAT YOU FILL CONFORTABLE WITH, AND IMPROOVE THE ONES THAT YOU LIKE THE MOST, I AM NOT A GENIUS, SO TRY TO USE DIFFERENT SKILLS WITH DIFFERENT BUILDS.