What is the best branching strategy to use when you want to do continuous integration?
As long as you understand principles, you can always re-invent the best practices. If you don't understand principles, the best practices will take you that far before falling apart due to some conflicting external requirement.
For best intro into the Mainline Model, read this: https://web.archive.org/web/20120304070315/http://oreilly.com/catalog/practicalperforce/chapter/ch07.pdf
Read the link. Once you got the basics, read the following article by venerable Henrik Kniberg. It will help you relate Mainline Model with continuous integration.
http://www.infoq.com/articles/agile-version-control