The book I followed for IGCSE Mathematics is from Dr. David Rayner. I found his exercises very good, but the explanations were vague.
I would suggest that you do a past paper, and mark it by yourself. Then see which areas you are weak at, for example sets or vectors etc.
Then you simply practice those specific chapters from the book.
It may also help to have topic based questions that are from previous past papers.
Hope that helps
If there is any particular resource that you think you might need, please post a topic in the IGCSE reference and resources sub-board.
Happy revising!