I have every class at 90, and I want to start working on the professions so what ones should I take for each of the classes?
Newborn, Are you looking to just make gold or are you looking to get the max out of your character during game-play?
Newborn, If you're wanting to max your character's game-play then you need to think of the main specialization of that specific character. Think of it this way: You're a protection Warrior and the only logical combination is Blacksmithing + Mining > Why? > Unless you are heavily geared or have a great raid composition, the best stat increase for you is the extra gem slots and tiny health boost you get from these > Okay..? > Well, if you are geared then by all means you don't need the stat boost from anything and you've already maxed out your play potential until the next Xpan drop.
Best thing to do is look at Icy Veins for each class. They tell you how to gem, enchant, reforge, and select professions for each class to basically min/max it. I know for caster dps you'd want to take Engineering for Synapse Springs and Frag Belt enchants. For my casting dps classes I also took Tailoring for the gear and "self only" emboss enchants. But, seriously, give Icy Veins a browse. They have some helpful information on that site.
Newborn, Lol, it was an example. Okay so you are a pure DPS machine. If you are a plate class then still, Blacksmithing + Mining are your best options. If you're a leather class then Engineering and alchemy might be more up your alley. Clothie, well then of course tailoring and Enchanting/Alchemy. Professions such as Inscription, Leather working(less you want the wrist cuff chant) are usless. Blacksmithing(gem slots), Engineering(Synapsis), Alchemy(pots), tailoring(cloth is a free material which doesn't take up a profession), enchating(same as tailoring) are always great. Jewel crafting is on the fence as you get 3 nice stat gems but, other then that it gives you nothing. Plate - Take BS and JC Leather - Take Engineer(synapsis is great for Rogues and Kittnes) and whatever Cloth - Take whatever (you're a clothie, no one cares about you)