for the remembering try to revise in parts (either with topics or in small amounts of time) so you don't overwhelm your brain

For formulas or other information your trying to learn put post in notes on doors or places you'd look at a lot. So everytime you see the note you can have a quick read and hopefully start to remember it

There are also things like listening to music, or creating rhymes or mind palace stuff, that can also be used to help remember (kinda have to try them out see what works for you)

Tutors can be helpful, or just with a friend. They might have a way that could help you. Or talking to them about it might be helpful to you to

For the test itself. Try not to stress. First do everything you can. Then try to answer all the questions. Even if you don't get the right answer, there can still be marks for working out. Then if you have time at the end you can spend time trying to fix anything you got wrong

on the day of the test, just as soon as you wake up, go over your notes or math formulas, or dates and events because they stick in your memory better. But you have to do it first thing when you wake up. My science teacher told me that, and it works mostly.