In order to master mathematical skills, you would need to regularly practise Maths. One way to do this is to work through a set of questions on a daily basis. The set of questions covers various topics and normally it would contain about five questions. This should take you about 15 to 20 minutes to answer.
Make sure you research a question before you attempt to answer it. Show full working. Note down any essential formula or method or small cards so that you can use as revision cards. Over time you will be able to build up a set of cards that will help you revise the topics.
You can download 5 sets of the questions here for free.