Money is the hardest part of this game. Without cash you can't get good enough gear to take on the harder levels. I have time to kill while I am buying and selling stocks to max out my money.

Look at this FAQ

I know it might be a bit tricky to read but it has some decent advice, but here is`some more.

The helecopter trick nets you 1,110 credits per day max. However, it takes more of your time then buying and selling stock.

The best you can do with Ventuno Stock is to buy at day 77 for 3540 each and sale on day 11 for 7022 each. That is a net of 3482 per stock sold. However, you can only do this between cycles. The best you can do on the first cycle with this stock is to buy at day 4 for 4664 each and sell on day 11 for 7022 each. That is a net of 2358 per stock sold.

The best you can do with Solid State Stock is to buy at day 12 for 8,805 each and sell at day 76 for 18258 each. That is a net gain of 9453 per stock sold. That is more then double the investment. After a cycle or two I wouldn't even bother with any other stock.

O your talking about that stock thing that gets you like 1 million credits after you go through one full session of 99 days... I never really had that problem... I cant find what to spend my credits on anymore...