By making your game different from other games, in other words make a lot of custom stuff.
Yeah that's the best definition on how to have people like your map
I couldn't have put it any better myself ^-^
Creativity and uniqueness are the two main entities upon which the success of the map relies.
Of course, a map cannot merely exist purely out of creativity, though, for example: if you are planning on making an RPG, your storyline can be the most well thought story of all time - BUT if you don't have the triggering and mapping knowledge to implement the story into a well bodied RPG, then it won't be such a success. (this is referring to the terrain, the custom heroes, spells, camera angles for a cinematic, ETC.)
So best way to start (in my opinion) is to start planning the plot and storyline, creating the heroes and custom spells and abilities and when your inspiration and ideas run out for creating the heroes and conjuring a plot, mess around with the terrain editor and lay out your map : like where the major city will be, where the quest sites will be, ETC.
Hope this helped
this is kind of the recipe I followed to start maps I never complete ('cause I'm a lazy person
)
Good luck with the map making out there