Hi there I put together a tutorial about working with modular sets of units.
I plan to add some more ideas and techniques I've come across working with modular pieces before. To make sure it won't get too long I plan to break it up in two versions as well.. One more step by step tutorial only going in on basics. And one with a lot of text going more indepth on things.
The idea is to have a tutorial that is pretty general and not so "step by step" howto build a specific set.
Anyway, you can see the "first draft" here: