Mapping For Monster Hunt

Before you start on a map, open the MonsterHunt.u package in the class-browser so you have access to all the Monster Hunt-specific stuff.
Maps should be more of a single player style, but make sure there are enough pickups for all the players and that there's enough space for a group of players to move around in.

Boss monsters should be in large spacious areas, the players must be able to concentrate on defeating the monsters and not have to worry about the surrounding architecture.
Make an escape route for the players to run through and place a MonsterEnd trigger (found in the classe-browser: Triggers → Trigger → MonsterEnd) where the players will run to end the level.
If you want to add bot support to your map (very highly recommended), you can use the MonsterWaypoint actor (found in the classe-browser: Keypoint → MonsterWaypoint). Just put the MonsterWaypoint actors wherever you want a bot waypoint to be, like near a button or a lever, or just along the path through the level. Set it's Position property to tell the bots in which order the waypoints must be visited. Set the first one at 1, the next at 2, then 3, and so on. You can also enter the Event tag of a particular actor so when the bot gets to the waypoint, something can be triggered to happen.

Be sure to add lots of PlayerStarts at the beginning of the level to make sure the players don't telefrag each other when the round starts - about 12-18 will be enough for a normal size map.
You can implement simple puzzles for the players to solve along the way, but don't use too many as players will probably get frustrated.
Feel free to use as many special effects as you like, in this style of game, the players will really take note an think "How'd they do that???"
Remember that there is no Translocator, so don't make any situations where it's needed to progress.
The difficulty of the map is important, start with relatively weak monsters and as players progress through the level, use stronger and stronger enemies.
Make sure your Boss monster is pretty strong, players will be disappointed it only takes a few shots to kill it.
Don't put any monsters near to where the players will start, they'll all be slaughtered as soon as they spawn.

Environmental hazzards (slime, lava, huge drops, etc.) are great, but make sure the boss monster(s) can't fall in, or it'll spoil the fun of defeating them.
Don't give the players the best guns at the beginning, or they'll mow through the monsters too easily.
Use the MonsterEvent (under Triggers > SpecialEvent) to display messages for the players, everything has already been pre-configured, just type the message and connect it to a trigger.
Set the boss monster's bIsBoss to True so the player can get extra points for killing him.