Have a good balance throughout the map. That is, make sure all the good stuff isn't concentrated into one part of the map. However, make sure everything isn't too spread out. Don't make it easy to find anything, you don't want a chest around every single corner probably.
Find a nice theme that's unique and hasn't been done yet. It can be a bit hard, but maybe you can take inspiration from some of your favorite stories, games, and such?
When creating the map and designing, don't make the environment too hilly and such. You want an environment you can run around in and such. If there's lots of two+ block cliffs inhibiting the thrill of the chase, it can get really claustrophobic.
As well, don't be lazy. Lots of maps have giant air pockets under hills certain areas because the creator didn't want to fill in these air pockets. It really can take away from the feel. Also make sure to try to make land realistic. Dirt goes about 3 or 4 blocks down then it's stone down from there. Don't have the whole land made of dirt, unless you plan on having the players dig though the entire map.
Make the map varied. Sure, quad symmetry is nice, but it can be boring. Having lots of differing parts of a map makes it all the more exciting. Whether you should head to this certain group of buildings, or to these bunch of trees. Make it appealing to explore the whole map, rather than everyone head to the same basic points every time to grab certain objects. Players like to bunch up in spaces at high points, enclosed areas with plenty of supplies, and etc.
Try not to build a base for the survivors before the game has even started. They really shouldn't have an impenetrable fortress by simply waltzing in.
As well, try to be careful making towers. It can be an easy fortress for survivors and a concentration point. They can simply knock out the ladders or camp them. Aim for things like stairs or so, or alternate entrances. Remember, you want to try to make every part of the map appealing to the eyes of the survivor. Not just the easy to defend tower. Not just the room filled with goodies. Not the fort surrounded by obsidian.
• Spread things out
• Keep it interesting
• Make the map exciting to play every time