First, prepare a Formulae Notebook to make Ready Reference for solving the problems.
Prepare Index page, write chapter numbers and number all pages of Notebook.
Write Chapterwise formulae and mention respective chapter-wise page numbers in the Index page.
Start solving problems in a separate notebook keeping Formulae Notebook handy. Write all the steps and calculations.
If your answers do not match with the answers given, first check your steps and calculations for errors, and correct them. If it does not match, then only refer to the Answers & Explanations or guide-book.
Give priority to Correctness. Once the practise exercises are over, Go ahead for question paper set or test series. Keep away Formulae Notebook and keep alarm clock to alert you about Exam Time of 3 hours or as the case may be. This way you can get the assessment of your speed.
Some necessary Tables of 2 to 30, Squares of 1 to 30, Cubes of 1 to 30, Rules of divisibility by numbers 2,3,4,5,9 & 11 may also be kept handy if forgotten.