1. Start by looking at your problem description and decide if it is a clear and concise as it can possibly be.
2. Write a list of the tasks that need to be done to solve the problem.
3. Translate the list of tasks into a sketch of the code. That needn't be much more than copying the list into the code as comments.
4. Flesh out the tasks one at a time. For each task test that it is doing what you expect.
5. Test that the overall code works.
6. Profit

You should apply the same critical analysis to your post here. Does it look the way you wrote it? (You can edit it you know.) Is it clear to anyone reading it? Can you improve it in any way? See I know what I mean. Why don't you?.