Yes, but you'll need to do a few more things this time:
First, be more organized overal. Don't have participants doing their own thing unless it can sync with what everyone else is doing.
Second, plan ahead. Make sure you have things like judges, rules, deadlines, prizes, etc. all set before you start making serious announcements.
Third, advertise it. Maybe even with its own site, but make sure everyone knows about it, and treat it like its a big deal overall.
Fourth, wait for the opportune timing. There are currently 2 mapping contests going on as of now, one being that campaign contest, the other going on
over here. It's probably best to wait until both are finished first.
That's about it, or at least as much as I can think of. It wouldn't hurt to throw in a fun, funky theme as well. Here are a few I thought of a while ago:
- Best UMS map with only 1 location.
- Recreate the entire starcraft Terran campaign in 1 map!
- Best map with only 1 unit between each player (any unit allowed, as long as it is only 1).
- Best movie/racing/defense/bound/madness/<fill-in-the-blank> map.
- Best explosions/briefing FX map. (just a mindless showcase of exploders, special FX, etc.)
- Best animated minimap.
- Recreate a replay as a movie.
- Best map at, but not going over, the CCMU limit (that's Cannot Create More Units: 1625 if I remember correctly.)