I have to wonder what the best way to make money is, given how extremely expensive certain big-ticket items are. It seems to just be working your job of choice so far.
A good way is simply Spamming Jobs, second is getting to Upper New Ark, talking to the Professor then accepting his Job, you will use like 1k Credits tho, but afterwards you can spam the Bugs and sell them off (Carry Bottles).
Actually you might use more than 2.5k for this so Meh? Anyway just Spam jobs, if you are Strong enough you can get in my opinion is the best paying Job bodyguard in "The Rock" your choice pal!
You WILL WANT TO GET A CONDO it is the most Well made and focused Characters, AKA BDSM!
Good Luck!