So you’ve started to level up and you want to grab some professions do ya? Well the professions in SWTOR are a little different than in traditional MMO’s. First they are called “Crew Skills” you send your crew out to preform the tasks for you, and second you can have 3. The categories for your professions are Crafting skills, Gathering skills, and Mission skills. They are what they seem, the Crafting skill allows you to craft gear based on your Crafting skill choice, the Gathering skills allows you to gather materials for crafting gear, and finally the Mission skill sends your crew on missions to gather rare materials or complete quests with great rewards for you and your companion.
Now you can have only one Crafting skill but any number of Gathering or Mission skills (up to 3) which leads to some amazing customization of your character and crew. Do you want to make money gathering and selling materials? or do you want to be a stand alone service by gathering and crafting your own materials? The choice is really up to you!
Here is the updated chart associated with picking the “correct” 3 combinations of skills courtesy of SWTORcrewskills.com

This amazing chart shows based on which class you picked which professions would best benefit your character development. For example, for Imperial Agent, both Armormech, Armstech, Cybertech and Biochem are appropriate Crafting Skills, and their associated Gathering skills and Mission skills are shown. So you have choices on which route you want to go, do you want to make your own armor and purchase/find your weapons? or do you want to be able to make your own implants and let your friends make your armor and weapons? a great system with endless combinations all based on your play-style!
Now the key concept is the fact that you send your companions out to complete the tasks for you! You can do this by first opening your crew skills window (default keybind: N) and select the profession and send your companion out to complete the quest.

This costs credits and can take anywhere from a few minutes to many hours (24!) for more advanced crafting or missions. You can have multiple companions out preforming crew skills for you, use the drop down box on the bottom right to choose the crew member to send out. just remember while they are away they can’t help you with questing! So be sure if you need your companion you haven’t sent him away on a crew skill task, or if you have simply cancel the task and summon him up!
The same concept goes for Crafting skills, choose your crafting skill and choose your item to build, then click Craft in the bottom right (it was hard to see for me at first!)

So when it comes to professions SWTOR has a very unique system with plenty of customization! More information on each particular Crafting/Gathering/Mission skill can be located at SWTORcrewskills.com an amazing website with constantly updated Crew Skill information! So if your looking for specifics I suggest you head over there and start searching!
~Booglerz