I have participated in many physics competitions (not so good if it is chemistry or mathematics) and won prizes. (Don't say I blow)
1. I don't know what grade you are in, so I can't give you a measure of the time to do the problem, but you can do it yourself and use a simulation paper (I personally think that it is enough to leave a little more than 5 minutes for inspection. After all, you have thought of it yourself, so there shouldn't be too many mistakes, just check the ones with a large amount of calculation)
You must concentrate on the exam (don't talk nonsense, because I was always absent-minded in earlier exams, and I think everyone has this problem)
Be sure to make a mountain out of a molehill, not a molehill. Some people make big questions first when they see the average score, which is wrong, because making a mountain out of a molehill can help you concentrate.
4. As the upstairs said, if you can't do it, measure it. Drawing is to enlarge the picture and draw it as accurately as possible (this is taught by our teacher himself).
Generally, there will be some big questions with long topics, but experienced people know that this is a gift, because generally, as long as you understand the topic, there is nothing you can't do.
6. Finally, you have no idea about some questions, or you think some questions are biased. You must not panic. Try to use what you have learned to make inferences, and sometimes you can make them (a bit like synthesis, which is troublesome and time-consuming, but effective, and you don't want to analyze complex thinking processes).
This is what I want to convert most, so I should get something from it.