Never stop training in a factory to increase effeciency.
More factories to lessen the mineral surplus I tend to get when I start pushing.
Closer cluster of factorys to increase speed (apm).
F3 factory cluster to increse apm.
Use more hotkeys to increse apm.
Better building placement to increase unit transportation and leave space for air deffence and air attack vurnabillity.
Less micro more macro focus at least until I got "less then 500 minerals" macro going.
Play more games to increase overall understanding and speed. <- NR 1 priority