Modular AS and target paths best practice

I’m re-writing a movie so that elements of it are modular movieclips, so that should I wish to re-use them, I can simply copy onto the root time-line. What should I watch out for regarding my paths in the modular clips? i.e. should I always ensure they are relative or absolute? How example should I reference mouse properties (e.g. _root._xmouse) which which will always be properties of the main movie root timeline?

Thanks,

t