"Principles of Problem Solving", pp. 54–59 (Stewart), is an extremely concise summary of Georg Polya's book How to Solve It.
You may find some of the ideas a helpful reminder of strategies you have been using, as well as some approaches to problem solving with which you may be unfamiliar. The section ends with a list of sixteen problems to practice problem solving.
2, 3, 10, 12, 14, 16, 17, 20, 31, 33