Build order and placement is important. Playing on instinct will only get you so far. You need to have a plan to reach the highest levels. Even a crappy plan is better than no plan. If event A occurs, you need to have a counter ready, if event B occurs, you need to have counter B ready. Early game plan A needs to lead to end game plan A or B, so long term plan is also important. RTS games are kinda like chess, you will never get past the intermediate skill level without a solid plan. Even if you have the best micro or instinctive play in the world, you still won't win.
If you really want to get good at the game, write down your strat on paper exactly and branch off the different scenarios. Then follow the branches on your paper depending on how the game goes. Focus on the ideal branch and then take other routes if things don't go the way you want. Sounds nerdy, but it "really" helps if you want to win. Tree diagrams work best :)
Those kind of techniques allow you to play better than everyone else but with only 1/3 the play time (so you can have a life). I hardly play the game (i'm not even remotely close to general with all accounts added up) but i still beat most people because of having a solid plan on paper.
btw, before you call me a big nerd........i'm in an engineering major. I enjoy playing games this way (ie: theorizing, designing, etc..). Plus i'm a former chess player (AZ champ at 11 yrs old :)
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