I assume you're talking about the first game (Alien Nations). The best thing to do to generate more income is convert your dwellings to large dwellings. Large dwellings fit 3 times more people and cost the same to maintain. If you keep building small dwellings, you'll be playing catch up as the more you build, the more food you'll need and the more income you'll need to maintain your food production. Large dwelling is the only answer.
First, don't grow too big too fast. I usually just stop building houses after building 4 of them. I research Metallurgy and Large Dwelling as soon as possible. Then build a mine, start producing iron and build large dwellings. Whenever you build a large dwelling, destroy two small ones until you convert all of your citizens to large dwellings. When you destroy small dwellings your citizens will move to the large one. Make sure to destroy them right after the large one is finished - that will ensure there's enough room for them to move in. This alone will bring you way more income than you'd have with just small houses. If you also research and build a Bank, you'll be rolling in cash.
Here's some additional tips:
- Shut down buildings that have standing fees when you don't need them. For example, once you mine enough iron for your large dwellings, bank, etc, shut it down - it'll save you 20 gold. You can also shut down police station when there's no criminals - that'll give you another 30 gold.
- Don't build too many warehouses, they cost 5 gold each to maintain. I usually find 2 is enough, that gives you 75 storage space
- To build a nice, self sustaining city, all you need is 3 large dwellings and a bank. That will give you enough income to maintain all the buildings you need to keep your nation happy, plus more to build up your cash reserve.