As has been said here, while FLcompanion is good, don't rely on it.
Get a ship, it doesn't have to be a big trading ship, something small and zippy (as in fast) is good as well.
Use that to run all over the place, hit every station you see and build up your own personal database on that ship.
Trade as you go, never spending so much that you will be short on cash if you get killed and lose your cargo, even if it means traveling with a half empty cargo hold.
If all else fails and you are hard up for credits, head back to Pennsylvania and mine that gas cloud for free stuff.
If you reach that stage you *will* have a place to take it where you can get a *much* better deal, even if it is further away.
Eventually you will have a very large list of places you can go to AND a good map of the universe as well.
Also, if you need help, ASK! It's amazing how many people give up without asking.