Cooking and Fishing can be raised together
Profession Details - Aside from Fishing, Cooking and First Aid, you can only select a combination of 2 of the following professions. Every rogue should get First Aid. Cooking and Fishing can be raised together at a later date and can provide some Cabal Alz significant boosts at level 60.
Alchemy - Used to make potions. Requires Herbalism to actually be useful though, many potions are used in different trade skill but you’ll find the most use from the Agility potions and healing potions.
Blacksmithing - You can use about 4 items total in this profession. Requires Mining as well. Not suggested at all.
Enchanting - Enchant your equipment and others with some pretty amazing bonuses. Requires green or better items to disenchant to increase skill though and therefore the most expensive and difficult skill to rise.
Engineering - The only skill where 90% of the items can only be used by fellow engineers with enough skill. It can make bombs (which can stun your opponent for 3 seconds, so great for PvP) and a large variety of unique items. Jumper Cables can resurrect someone, Shrink Ray reduces attack power by 250, and Death Ray inflicts a ton of damage. It can also create pets to help you out in battle.
Requires Mining to increase the skill, this should be the profession you select at 60 as well as enchanting. The major reason for being an engineer is that you can buy 99% of all the craft able items from every other trade skill BUT engineering. You need to be an engineer to use engineering items.