In order to get better at this game you really should take the time to study it and practice it. Pro players practiced for hours and hours to become very good under pressure at tournaments. Whether you want to take your game to that level or you just want to keep it as a hobby you need to practice more and read on to learn more.
My first tip for you is to stick to one race. Some players try to be good at all races and play as random. There is really nothing wrong with it. But there is a reason why most if not all pro players do not play as random.
Each race has a different play style and different controls to memorize. This is what starcraft 2 is all about. You need to master the controls of your race. That way you drastically increase your actions per minute. You actions per minute determine how fast you are.
Some players are so fast they can achieve over 300 actions per minute! You do not have to be that fast. After all it is not about how many actions your perform. It is about how many quality actions you perform.
You need to decrease the amount of unnecessary actions performed. So basically you should only focus on performing as many quality actions as you can. Outplay your opponent. What I like to do is make a list of every that I need to keep track of.
I play asterranso my list of chores includes producing marines and marauders at my barracks, get upgrades at the engineering bays, expand, producescvs, and so on. So make sure you keep up with production while harassing your opponent. This is how you outplay them. You need to look for gaps in their playing.
Maybe they have an expansion that is completely vulnerable so you can go harass the workers without having to bring your entire army over to attack them. Check out these starcraft 2 cheats.