Looking for more codility strategies

I am looking for some general strategies for solving Codility test. There are some tips that I can come up with:

• Read it carefully
• Think like Mathematic (if you are good at math)
• Find ways around the problem, sth is not difficult if you can convert the original problem to another easy problem with a little twisted. Ex: Prefix Sum
• Find the easiest solution first, then try to improve it if you can. This helps you to show your incremental thinking to the employers/firms even if you don't get 100% overall.
• Add more test cases: CORNER CASES(null, 0, greater, less than, complicated)

Please help me, thanks guys.