All your points are correct, Mega. Except one:
No every serious mapper does release only every 10 map or so. Take sock for example (he made many maps for Enemy Terretory, like Fuel Dump). He just works on a map for 5 or 7 months, while collecting textures through his own digital photography, searching for sounds for the athmospheric and creating a really nice brushwork.
One thing he always does: If he spots a new technic to do something, he creates a testmap (most times they aren't smaller than a quarter or a half of ATCS), and plays around with the brushes to see if it looks good. Thats the same way I work.
Another thingy is: Those "map on a paper" is not always the best tactic. Well ok, for the first impression its ok, but then you don't know, if it is realy practicable. So pick the Caulk-Texture (and enough time), and put the basic of your map together. Then you see, if everything is in size and you have a basic of what you will do. Then exchange the caulk-sections with the according parts of your map, and don't forget to make details to detail-brushes.
To the textures: Evil's textureset is used quite to often. You can find textures of him in nearly every official Tremulous map. It's true, you need metal-textures for the most maps, because its the theme of the game, but you don't have to use always the same textures. New mappers may search for new textures on wadfather or different texture depots, advanced and experienced mappers should go out with their digital-camera (come on, everyone got one today), make photos and create their own textures in Gimp or Photoshop.
Then use different light, not always a white light. Dangerous areas should be marked with red lights, maybe glowing or flickering (its possible, thx to ydnar). Through those instruments you can make your map very athmospheric.
Another thing is sounds: I always run through maps, and everything is silent. The only thing I can hear are the fireing, slashing, pouncing and jumping people. So create things in your map, and add a specific sound to them. Thats something I hate in the station map: You see gas, escaping from a pipe, but you don't hear it. If you are a serious mapper, you have to put an apposite sound to this. But you don't have to make the sounds by yourself! There are so many sound libraries out there in the internet, where you can get sounds for free for any purpose.
So in the end:A really good map does not only have a good gamplay. Its true, this is a important thing, but everything else must fit. You need a good and detailed brushwork, the right lighting effect and apposite sounds. If everything is correct and fits together, the players will thank you for you great work. Else it will be only another ATCS/Tremor-style map, with less quallity.
And please, don't release a bunch of beta-maps. It is a pain to see hundreds of maps laying around on the servers, and only 15 of them are realy final. Search 10 guys, a private server and test the map with them. Collect opinions and improvements of them, and change your map again. Repeat that, until those 10 guys are happy with it. Then you may release your map. Here, don't forget to put a readme-file into your zip/pk3, so everyone knows, who made it and has some infos about the map. You may read, what sock writes about it on his website:
http://simland.planetquake.gamespy.com/pages/articles/readmefile.htm
