I was the CD of the Combat events when we held them at our club. If you already have a CD, and you have read the RCCA rules for the different categories, then just pick which categories you will allow at your event and go for it.
The biggest hurdle to jump is the field layout. To establish separation between the spectators and the flight line, nd the flight line to the combat line on an established field is a headache. In our case, we had to "displace" the normal flight stations to the far edge of the runway, and use the short grass adjacent to the runway as the landing area. The combat area was about 50' in front of the flight line. No combat allowed on the near side of that line.
Here is an aerial view of our field:
Due to the shelter being in a fixed position, we had to do the changes as stated above.
It is not rocket science, but it is hard work to plan and prepare for an event. Feel free to ask more specific questions either here or by PM.
Rafael
Edit: Added the picture