Just 10 general guidelines to improve your game please take it for what it is.
1) Make A lot of drones but not too many.
2) Look to take an advantage as early as possible by attacking well or defending a push well and keep the advantage.
3) never forget about detection.
4) scout well in every mu but especially with key overlords vs Protoss and Zerg.
5) Avoid fighting when your units are in a bad position or you dont have quite enough to battle yet.
6) Never cut corners in necessary defense.
7) Unit Composition is Super Important in every battle so choose your units wisely.
8) Creep spread is Very important ESPECIALLY Vs air to connect your bases for queens.
9) Don't forget to switch tech when u already have decent tear1/2 units.
10) Never EVER get supply Blocked.