The SCons Recipes in the wiki is a good place to start. In addition take a look at other projects which use SCons, e.g. the Ardour build system. If that doesn't cut it, there are a few third party SCons extensions you may want to take a look at:
To the best of my knowledge, there are no SCons best practices which were agreed upon. The SCons community seems to favor adaptability over "canonicalization". It is not hard to design a decent SCons-based build system from scratch, though. (Once you have understood how VariantDir works, at least.)