Now I know I am still learning this game but I would like to pass on some knowledge I have learned from playing so far. The most popular issue we new players deal with is how to get credits. This is the way I am doing it and it is working so far. I hope this helps answer some questions.
These are my 3 choices for crew skills
1. Archaeology
2. Slicing
3. Underworld Trading
Results achieved so far
1. Archaeology - I have picked out this one as I am able to not only send my companion(s) out on missions but I can find spots in the different areas I am leveling and get those free materials. When I sent my companions out I send them out on the Power Crystals as i find those to sell the fastest and bring in a good profit.
2. Slicing - I know everyone says pick slicing for making money and you know what, the are right . Not only do you make a little credits but you also receive schematics and other goodies you can sell for decent credits. Also you can pick up spots in those areas you level just like Archaeology so that = more free credits.
3. Underworld Trading - While this is strictly a mission and you can't find spots on leveling areas you do...or at least I have... made good money from doing these missions. I only pick the Underworld metals and not the other ones. I get a good selection of purple materials which sell pretty well.
Tips:
1. SELL EVERYTHING - Including those greys, everything gives you credits. Make sure you sell those Bind on Equip pieces too since every now and then those will sell on the GTN. Don't forget if your short on inventory space and your in the middle of the world you can send your companion out to sell all grey items you have. They are only gone for a minute so it's worth the wait.
2. Get those gathering spots while leveling - This not only helps you level your crew skill but it also gives you free materials you can sell later. Even if you see a few mobs around the spot, just kill them (free exp) and get it. It won't take up much of your time.
3. Sell on the GTN in small groups - Don't sell in large chunks. I try to sell in this order - Greens = stacks of 20, Blues = stacks of 10, Purples = Stacks of 2. Doing it this way seems to sell the quickest. And make sure you look at the GTN prices to make sure you aren't overpricing it or underpricing that way it has the best chance to sell.
Ok that is all I can think of that hopefully can help everyone just starting out. And if you don't think this is a workable strategy, so far through level 24 with the latest batch of materials I have earned 486k credits which I think is a good amount for a new character to work with. I hope to earn enough by the time I'm level 50 to pick a crafting skill and level it up. We shall see. Anywho I hope at least 1 player can use this information to their benefit.
Have a great day everyone