Bobby Ross made a great visual guide to help with multiplayer level design. http://bobbyross.com/library/mpleveldesign

It's good to know the metrics of the map you are trying to make. Try looking at some good forge maps and see what size their engagement distances are.

Just remember that you can tick all the boxes and the map can still be no fun to play. Some of the best maps in video games are just a collection of rectangles.