Start simple and iterate from that.
For example in GiTC:
- Send 2 troops from your factories to not owned factories every turn.
Very simple, far from optimal, but it's a start. Now you realize that to win a battle, you must have more troops than the opponent. So 2nd heuristic:
- Send nb_of_troops + 1 troops instead of 2, where nb_of_troops is the nb of troops of the factory you attack.
Then you might want to take into account time of travel, ie enemy factory will produce units and possibly receive reinforcements.
The main danger is having a ton of ifs and different ideas performing against each other. So try to keep your ideas simple.
This blog article from Bob might help you understand the philosophy: