Don't bother trying to discover purple schematics while levelling. Too costly, time-consuming, and it will be obsolete in 2 levels. Don't send companions away on missions for the gathering crewskills; you can get that stuff for free out in the world. Excepting: (some?) crewskill vendor items can also be obtained from missions, and they are/should be cheaper that way (and can crit).
Sell everything higher than greens. Even if it's something you can use, just sell it, it will be obsolete soon and you can get to 50 with quest gear. Delay purchasing skill ranks you don't need/don't use. Including mounts. 10% faster speed is about all you get for it.
And above all, DO THE SPACE MISSIONS! They give ludicrous amounts of credits.