Review the chapter. Read it several times to gain a complete and thorough understanding of the author's intent, main idea and ending. Write down notes to make the process easier.
Outline the chapter. Organize everything in order. Listing things chronologically or in some logical fashion allows you to implement these notes into your summary without it seeming too sporadic.
Write the main idea in your summary before any other details of the chapter. Doing this allows your summary to start off strong, showing the chapter's main focus before jumping into anything else.
Write about major conflicts and events if they have an impact on the chapter. Mention them in a concise manner and move on.
Edit and revise. Read the chapter again and compare it to your summary. Be sure that you've covered the main idea, supporting points, characters, major events and conflicts in a manner that is both accurate and easy to understand.