Do what your doing until you get to about 16k.
If you die, don't worry just take the free ship and keep building up the creds.
Buy 2 gimballed lasers for the Sidewinder.
Goto LP98-132 and to the asteroids.
Scan and kill NPC ships with a wanted status. Each kill will get you anywhere from 50 creds to 1500 creds. You can fairly easily make 10k or more in 30mins or less.
As soon as you see another player ship, run, until your more confident at fighting.
All power to engines, get out of there and hit your C key to engage warp as soon as possible. Don't wait, don't think about it, just go.
As soon as you enter warp, (well wait maybe 1 second) hit C again to drop back into the asteroid field, but usually a different instance.
This will also save your game. I'd recommend doing this semi regularly even if you don't see another player to save losing chunks of cash such as 15-20k due to a crash to desktop etc. As you can probably guess this has happened to me too many times to count.
Check for other players, if none, kill pirates, if you see one, get out of there etc.
This will get you into an Eagle at least in next to no time at all.
Hope that helps.