Example:Workers upkeep:-19
Army upkeep:-2
Agent upkeep:-2

Well, to lower upkeep if you had those statistics you would either disband agents or disband your army.

Although, I would recommend that instead of lowering your upkeep you increase your worker income. You can do this by

a) Increasing the level of your 'food' structure
b) Capturing 'resource OPs' which are scarred around the world

Good luck, remember that the forums are always open to questions and filled with answers.

More info on all the different types of OPs HERE

More info on structures HERE

More info on Agents and how to disband them HERE

Here's what I do.

1. Try to get as many resource ops as you can.

2. Never have more than 3 agents at a time.

3. Have a reasonable amount of outposts, no more than 5 to 8, unless you can sustain a larger amount of them which I'm assuming you can't since you asked this.

4. Buy reds and become a supporter, you get alot of benefits from that, but if you don't want to buy tokens, just vote every day and save up until you can purchase a small worker boost. Here is the link for voting by the way,
http://www.battledawn.com/?p=vote

5. Good luck and have fun! Oh and listen to ferr3t, he knows more than I do. But listen to me to..... yeah you get it lol.