I NEED HELP WITH PLAYING LATE GAME

So i like doing 1v1s and i start off pretty well (usually up on units, and have a good position) but then in after like turn 10 i start getting fucked over so badly, if anyone has some advice about how to play late game that would be wonderful.

note: i did read the post by Zenith on this, but i would like more detail if possible.

thank you : )