the most thing that was shaping a big block in my way to advance is getting tensioned and stressed during the contests; that would make me not able to solve even the problems that are way easier than my level, I think most of you can relate. So how to overcome this trouble or at least mitigate it so you can do better during the rounds:
Try to imagine the worst-case scenario and how would you deal with it, for instance, how many points will you lose at worst? 100? 200? so what you can compensate them later so why on earth would I tension myself like that.
make some drink you like before the contest that would help, and take a short break (5 minutes or something) in the middle of the contest if needed to have a snack and relax a bit.
watch some streams of top-tier contestants taking part in contests, such as SecondThread, tmwilliamlin168...etc. you'll see that these people are competing at the GM level although, they're so relieved and not stressed at all.
these are the tricks I used to mitigate this catastrophically bad habit and they helped me a lot to improve my performance. if you have any other tricks to handle it, please drop them. wish you all good performance in the upcoming rounds and high ratings.