So every 2 weeks my school holds an assembly between its houses. These assemblies are run by the homerooms within those houses (8 houses - 7 homerooms per house - each homeroom has students from yrs. 7-12 in t) and as it's our homerooms turn around the schools exam period starts my teacher decided that as my homerooms year 12, and "have the most experience with studying " I would give the house some advice on how to study.

I'm not very good at studying.
I don't really study.
I just wing it, hope for the best and manage a B or C (I pass).

Would anyone be able to give me some ideas/tips on what I could tell them?

Google study tips, make a list of things you know other students do, ask other students how they study.

You are in year 12 and you don't know how to subtract?

https://www.askmehelpdesk.com/high-school/math-811391.html