this is the type of game where you do not get good over night.
Here are some tips you should imply every game.
1. constant scv production
this game is an economical game its the most important part
2.practice builds over and over
make it so its second nature to you
3. macro is important!
while fight build more units constant production is key
you must i mean MUST SCOUT! if you do not scout how do you know what your opponent is doing?
in the mid to late game one base is not enough you must push out and expand when you can
this comes with practice but learn when to attack and when not to
7. attack and expand
the object is to wipe out his army but if you lose a fight while taking out most of his forces than obviously he will not attack so its safe to expand
8. if your enemy are is an immobile one as in he is turtling then this mean you exploit his immobility by dropping his base? expanding? attacking his expansion where he cant get to in time? exploit his weakness and while doing this expand