Firstly, read the problem carefully and multiple times in order to try and understand what it wants and what topics are involved in the equation. This helps you narrow down the formulasthat you can use. If you're still confused, try paraphrasing the problem.
Next, draw the problem out with the help of diagrams and models to help visualise the question and look for any patterns. Write out a list of what you need to obtain in order to get the final answer and make use of all the figures you are given with the previously narrowed down formulas.
Lastly, if you are still confused, try to make an educated guess of what the approximate answer may be or lie near to and work towards getting a similar number.
Adapted from https://www.wikihow.com/Solve-Math-Problems