Practice makes perfect of course. Every question you do from now on should be timed - the first time you try it. Then spend as much time as you need going over it.

Figure out the more efficient ways to do it, ways you might not have noticed the first time you tried it.

Figure out how and when you'll decide when you have to pull the plug on a problem, make an educated guess, and move on. (You will have to do this - nobody can get around it, not even those of us who teach this stuff!)

Keep a log of your mistakes and why you made them. When you find patterns (specific errors you tend to make over and over again), figure out what you can do to stop yourself from continuing to make that mistake.

I don't know whether it's possible without additional info. (Well, I mean, anything's possible...) Have you taken a practice test recently? What did you get?