What's a Credit?
There are two ways to collect credits. One is to kill enemy ships. The other is to fly into another system and fly through mineral chunks. Collecting minerals is the quickest way to move up. Minerals are scattered throughout the asteroid field at the Aquarius system, and some are also inside the the big structures at Tauros and Scorpio.
Here's a picture of a
mineral. They come in various colors. Some are worth more credits
than others, which is determined by what color they are.
To pick one up, fly right through it. Novalogic has mentioned that this is bad in the single player game, however. : )
Depositing Your Credits
The bigger your ship, the higher its credit capacity. At the top of the screen is a reading of how much you're carrying, in terms of your maximum capacity. When it reaches 100%, fly back to your base and deposit them.
To
deposit your credits, fly through one of the green globes. Doing so will
raise your Personal Experience as well as your Team Experience. If your
team has enough experience, you will all advance to the next Tech Level, and new
weapons and add-ons will be available.
When your Personal Experience is high enough you will advance to the next player level, and enjoy slight increases in speed, power, etc...