(a) Achieve in practice. Remember that, in the end, it is necessary to answer questions by yourself without any help. Prepare for that by learning the material and developing your skills. Keep trying. If you're working through practice questions and get one wrong, keep coming back to it and similar questions until you can do them yourself. Reading someone else's solution, or getting help from another person, can give insights and helpful pointers to things that need work, but that's only part of what's needed. Like swimming or cycling, mathematics is something that you do. It is tough to learn how by reading about it or watching someone else. When you have learned the concepts, and accumulated a lot of experience using them through regular practice, you'll have confidence in your abilities. Keep your goals in focus.
(b) Start early. Begin thinking about assignments the day you get them. It takes time to think about the questions and how the different methods you know might apply. Start studying for tests at least four or five days beforehand. This will give you lots of time to fill in any blanks in your understanding.
(c) Always start with things you can do. Look over all of the questions on every assignment or test and pick the low-hanging fruit first. Build on success.