Easy hack that is very helpful but people often fail to do it: Do things in the exact same order every time you do them when trying to get better at something. This instils habits faster and saves you cognitive load as you are able to operate on autopilot. You also are able to more easily ballpark potential efficiency improvements. Basically, the first step towards refactoring is to actually algorithmatize your task.
Another gem from xkcd: Is It Worth the Time? It visually answers the question:
Of course, he's not the first person to ask this question, but the visual is handy. Note that the times are calculated assuming you'll save the time over five years.
For example, I've been pondering how to shorten my showers. If I can shave off 1 minute daily, I should be willing to invest up to (but no more than) an entire day to do it. If I think I can shave off five minutes preparing my breakfast, I should be willing to spend up to six days attempting to do so.