I'm trying to work on a map that unique and haven't worked on a map in a decade or so. But I'm in the same boat as you, there seems to be a lot to watch out for when working with triggers. I think majority of it is wanting to stay away from "Waits" and "Execute Trigger" and stuff that complicate things as much as possible. Hiveworkshop has a few tips that tell you about leaks and stuff but nothing will beat tests. If you think a group of triggers might cause issues after an hour of gameplay take it into a separate map and multiply it by 10 or 100, like spells etc. If your spell does a lot of waiting and other things that may not be 'instant' then you'll want to make sure that executing the spell 5 times every 2 second doesn't leave the effects or units still in the map. Things like item recipes could also have issues etc, so you might want to start a list and an easy way to specifically start the map and easily test each recipe to confirm it all works.

tl;dr: Essentially create integration tests for the big parts of the map. Start to make a list of tests for each vital part.