What to do when you feel you aren't getting better

Most of this comes with experience so you have to be patient...

1) While sparring I try to think tactically and make sure that my actions and reactions are correct while maintaining proper footwork, guard position and punch technique.

2) While shadow boxing I focus 100% on form and speed.

3) You'll learn that the way to land any punch(straight or otherwise) is to make sure that you're always in a position to fire so that you can exploit an opening when you see it(i.e. opponent lowering guard while punching/telegraphing punches etc.)

You have to be patient. It's a process so just focus 100% on fundamentals for the first few months to a year while enjoying the day-to-day process of getting better mentally and physically.