The list below holds good suggestions. I'd rate visibility very high. I also would add safe footing. Especially as it will be your home course and you'll probably be practicing and racing on it the most, you don't want too much of the footing that causes sprained ankles and such.
From a competitive standpoint, a tough start is good. If your runners get used to a tough start (meaning some hills and heavy footing) they'll be able to cope well with other courses when they travel.
1. Start/finish area - Make sure you create a good start where you're not funneling runners down instantly and creating a bottleneck and a finish that provides a good view for runners and spectators. Also make sure that your start/finish won't bog down in wet weather.
2. Turns - Make 'em big enough to handle a lot of runners or put them late in the race when the field has thinned.
3. Visibility - Coaches and whatever spectators happen to come watch need to be able to see what's going on.
4. Cheatability - Avoid creating areas where runners are tempted to or can inadvertently cut the course.
5. Navigability - Someone should be able to figure out where the course goes without having 50 officials pointing out the turns. It'll also mean you need less course