I got my first (and so far only) map accepted after 2 tries. And looking at the map before and after revisions, it's clear now what needed changing, what was perfectly fine, and what needed scrapping altogether. I think it's really important to be able to interpret what the map judge has to say as their criticism can tell you how much scrapping and revision you need to do. Also asking the map judge themselves, or other judges, can help too.
Additional help from friends can help too. I got some flack for having 3 friends help revise my easy map XD , but honestly I'm just glad to be able to get a map accepted. it's pretty much one big cycle of learning and improving the first time round.