1. Notice when your starbases are overlapping coverage. Like when you have 3 in an area each taking 1 resource, where one base could easily cover all three. And it's sorta deep in your own territory... delete some. Place them better.
2. Once in awhile re-evaluate your planets and build the buildings that are advantageous to that particular tile now that you have the tech- tear down the old crap. And get with the hub and spoke program better. That's not too hard mathematically to sort out.
3. Never ever ever build +% modifier buildings that are designed for neighboring tile building benefits in isolated hexes. Just never. The maintenance alone screws you. Better to leave the hex empty in fact.
4. Notice when you have a mining starbase... harvesting NOTHING. OMFG. And especially when it's deep within *my* territory... What you doing spending maintenance on that. Delete the starbase unless you really really need that LOS. Which, trust me, with the amount of scouts you have flying around, you don't.