Get Big Fast?
The bigger your Harvester, the more resources you can gather at once - but the slower you move. At first it might pay to stay small and make lots of frequent trips until you've powered up enough times.
Got My Eye On My Money
Don't just pick up resources willy-nilly - keep your eye on the market board that shows prices, and go for the big-ticket items first. Remember: the market changes, too, so make sure the upcoming price is high for anything far away from home base.