Be efficient with your time as well as resources.
Don’t spend too much on building structure until you need it. It’s really easy to get carried away here and then you have no weapons.
Place expensive things first, like mines and tech, because they take a lot of time to complete. While they’re building you can work on your base without losing time.
Don’t defend too early, make your defenses right before you need them. For example, if you know you’re going to get hit by a cannon around the 5 minute mark, spend the first 4:30 building up your economy and getting weapons of your own. Then prepare for that cannon.
Look for weak spots to target on the enemy base. Turbines, doors, weak foundations, cores, etc. In almost every game you can watch the replay and see some place you could have shot earlier and won the game. This as true for everyone, from top players to beginners.
The AI prioritizes rebuilding damage over progressing, and it’s quite stubborn. If you destroy something minor like a machine gun or a sniper, it’s going to keep replacing it, even at the expense of getting better weapons.
The AI also prioritizes certain targets on your base. It has a real grudge against turbines and snipers. You can take advantage of this by placing them as distractions to encourage the AI to waste its shots, hitting unimportant areas like sandbag walls.