Mathematics Exams Tips and Tricks

Hi all, I'm curious if there are resources where I can learn more about various tips and tricks I can use to check my answers to questions in an exam setting. (A-Level Mathematics).
For example, I know I can use my calculator to check if my x value for a min/max point is correct by using the differentiation feature. Similarly to find the decimal value for a definite integral and compare the to the exact value I find on my won. Or that I can sub in various values of x into a partial fraction (that I calculate) in order to check if it matches the original f(x). I know a few more too.
Just curious if there are other such tricks/methods I can use. I'm homeschooled/self-taught so haven't had much of a chance to learn these types of techniques. Thanks, and apologies if this is a little vague.

There are some general/useful hints at
https://www.ocr.org.uk/Images/596258-exam-hints-for-students.pdf
and its good to validate / check your answers as you suggest, and probably the best way is, when youre doing a paper (or just after), try and validate each question/answer by estimating, calcuator, validating solutions in the question, sketching functions, ...

Thank you, much appreciated.

No problem. Tbh it would probably be better to ask about specific question(s), so if you cant see how to validate a particular solution it would be better to post that question along with what you did.

Yeah fair point, although I don't have anything specific in mind for the time being. Averaging around 92-95% on most papers. Mistakes tend to be 'silly', so just looking for ways to reduce them (aside from simply being more focused).