A typical examination question in Mathematics will have several parts to it. Some parts (most usually at the beginning of the question) test your knowledge, by asking you to reproduce "bookwork", i.e., material presented in the lectures. Really, these parts test how well you've revised. Occasionally, especially in certain more advanced courses, there are entire questions that are bookwork. In some courses, some pieces of bookwork come up in the exam almost every year. In other courses, hardly any bookwork is set explicitly.
Tip: Figure out which pieces of bookwork come up most frequently, and make sure you can answer those questions easily and quickly.
You would be surprised how many poor attempts at routine bookwork questions we see every year. These are the parts of the questions that we expect students to be able to do.
Other parts of examination questions involve a "problem". In a "Methods" course, this will typically involve you applying a known technique from the course, and again this is something we expect you to be able to do. In a Pure Mathematics course, you might be asked to prove a result, or to apply a result in a particular setting.
Tip: Sometimes (but certainly not always!), the first part of the question is intended as a big hint as to how you should approach the second part.
Many exam questions, especially (ideally) those that are otherwise very routine, have a last part (a "rider") which is more challenging than the rest of the question. This is quite deliberate, and the intention is to test whether you've really understood the material.
Tip: Do try all the riders (they're not always so hard after all!) but don't waste too much time on them in an exam if there are other things you can tackle instead.
Students sometimes seem to be very annoyed that they have to do something clever to get 100% on a question. Don't forget, in many other subjects it's practically impossible to score 100% on a question!
Tip: Make sure you've answered all the parts of the question. Sometimes you're asked to do seven or eight things, and it's easy to overlook one.