I am finding for the good resources to learn OpenCMS. Please provide the guideline/best practices to develop an OpenCMS based websites. Any kind help is appreciated.
There's a wiki.
There are books available. I've only read this one, which was helpful but is targeted more at improving an intermediate skillset rather than being an introduction.
There is also a mailing list.
Of course, you can also subscribe to the Stackoverflow OpenCMS tag feed, although it doesn't see a lot of action.