Unlike most RTS games, infantry arevery useful as they can block unit movements and lets you form walls of infantry that must be killed with weapons.
This game lacks rally points so make sure you move units away from their training building often to avoid bunching them up.
Miners are cheap so don't go out of your way to protect them.
Base defences are strong at attacking, but have low health. Without support base defences have a hard time staying alive long enough to do any serious damage, so support your base defences with mobile units stationed at the entrances to your bases, as even a modest attack will shoot its way past turrets. Support units will help draw fire so the turrets aren't focused on, allowing the turret to do more damage.
The AI doesn't seem to cheat with funds. If you keep destroying it's miners it will eventually run out of money. Do this whenever you can. The Ai is usually not very careful about defending its miners and sometimes they can travel far away from the enemy base in search of resouces. A few Troopers can easily destroy a miner before the AI can do anything.
Use the terrain to your advantage. Arrange your base defences to take advantage of naturel barriers in the level. If for example your bas is in a valley with cliffs put your turrets alongside the cliffs and place your troops between them using the cliffs as "walls"
You can see enemy indicators on their buildings. A blue dollar sign means the faction doesn't have the money to perform an action, such as repairing or training troops, a lightning bolt means the structure is unpowered and a spanner icon means the structure is being repaired. You can also see a yellow progress bar for building structures or units on enemy buildings. Watching these symbols can be very useful to know if the enemy is creating reinforcements and when you have powered down an enemy base. Just watch for flashing bolts on their turrets and you know it's safe to just roll in past them or pick them off while they are helpless.