The rest of this possibly endless, vast, deep series is right here.
Just one best practice today.
Keep the Map Size Manageable
Just as an actual physical tip, keep your map size manageable for you, the GM.
I've occasionally complained about poster maps. Poster maps are cool, but how do you use them face to face? Lots of folding, creasing, and concealing, or just plunk it down and say "You know the layout" or what? Too much for me.
I use either 8.5 x 11" paper or 11 x 17" paper, because I have access to both easily. It's not too difficult to copy 11 x 17 on a normal printer, either, and piece together with tape, either.
Beyond that size, I find I'm folding, creasing, and otherwise mangling the map. It gets to be too much to keep in hand. It's vastly easier for me to map on 8 squares to the inch 8.5 x 11" paper than on twice as much 4 squares to the inch paper.
This does mean it's hard to communicate detail, put down pretty little icons, etc. But it's much easier to do the macro level navigation if the paper is easy to handle.
11 x 17" is the outside of size for me, if only because it can be folded in half. The times I've tried different sizes (smaller paper, or legal size) it's made the actually carrying, copying, storage, and not losing parts of managing a big dungeon too hard.
Corollary: Keep the Maps Separate
This one is for publishers and would-be publishers - put the maps on separate, map-only pages in your PDF or in separate, map-only booklets in your physical book. Please. Page flipping is a nightmare.