How do become good in Starcraft

Well, first of all, read the manuals, then know all the unites for Terran, Zerg, and Protoss. Use the campain guide to guide you through (for best results, don't use Power overwhelming). These will help you be the best. Also play online in battlenet.
This might be good.But there more that the manuals didnt tell u.Like how a zergling attack the marine and not a scv
imagine this
4 zergling10scv1 marine
if u surround the marine with all ur scv so that the zergling cant attack the marine then the zergling will just run around the scv circle!Because the scv is not attacking the zergling and the scv is not a infantry unlike the marine so in order doing this the scv will not get attack but if it is attack u can use them to repair each other! so 1 marine can kill over 200 zergling if needed!Also u need to learn the Research like how in (BroodWar) A hydra can turn to a lurker but!u need these building and technology.
Hive+Hydra>Hydra+Lurker Tech.
that is the formula for a lurker also u have to under stands about the other technology that other race has like how the lurker can be invisble ,but remember the fastest race that can c a lurker coming is a zerg since they have overlord!
Here is a little Detector i made for u
Terran has 2 detetor -Turret is the fastest why of getting a detetor since u only need a engine bay building but a science vessel take much more building and add on to get!
Zerg has 2 also a spore that can also be easy to acess and much easer the overlord!
Protoss has cannon and observer!
In south Korea Starcraft is like the nba +NFL combine !
These Starcraft player there have play sc for over 8 year and can make over 1 million $ doing it!
Imagine a person who understand a sport will know much more about each player stats and understand how or when the player can either weakness or strongest point of the player!
as to a nub who don't know anything will be defeated in second !