In my opinion Terran is the best race if you're good at micromanaging, and lots of fast clicking.
The build order should be 7th scv barracks, 8th depot, 2 more scvs. barracks and depot will finish at the same time, and you should have enough money to make 1 scv, 1 marine and start building a bunker. If you wait any longer and a zerg 5 pool rushes (spawning pool on 5th drone) you will be set back a lot.
No matter what you build as a Toss or Zerg, Terran has the perfect counter. Is your toss opponent Zealot rushing in the beginning? (can be seen by 2 or 3 gateways early before cybernetics core), ever seen stimpacked firebats tear through zealots. If they go heavy dragoon, marines + tanks will win. Goliaths + Cloaked wraith will beat Carriers. Against protoss it's always advised you go Heavy Metal (at least 4 factories, and all you make is tanks + goliaths), unless they go heavy zealots in that case you make firebats. Some people say to use emp shockwave on high templars, but I prefer to irradiate them.
Against zerg, Terran is even better. Tanks + marines vs hydralisk. firebats vs zergling + defiler. goliath vs guardian, marines vs mutalisks. Don't worry about ultralisks, no one makes those.
The most important thing is to always know what your opponent is doing and just make the counter for it. If you're ever on battle.net and want to play a game with or against me, my handle is prodigy.69 (don't forget the "." I usually play broodwar, but i'll play a game of vanilla sc.