These are my suggestions:
1. Make sure you have someone in the city where the regional is being held to handle all the logistics. If that is done well, and planned well ahead of time, attendance will be good and people will be happy.
2. Schools are always good for locations to keep costs down. Our recent regional was cosponsored by the NLG Foundation, so we were able to get the school at no cost. However, I wouldn't worry too much about some loss of money, as a successful regional will lead to new members and increased dues and maybe even some donations.
3. Get information out early and often about plans as they develop. The more people keep hearing about things, the better the attendance, which is the surest way to avoid losing money.
4. Decide on program content as soon as possible, but be flexible as conditions change. Make sure that there is someone responsible for each part of the program and check up to make sure it is being organized.
5. We did well this year with a kind of ad hoc, de facto organizing committee that was composed generally of the RVP and national officers in the region, our regional staffperson, the person handling the logistics and the people responsible for the various panels and workshops (there was some overlap). We were in frequent email contact which allowed us to deal with things as they developed and, in fact, expand the number of workshops because of the large number of attendees.
6. If you can, solicit input from the region about what people want on the program (and then encourage them to plan it).
7. Assuming you have a weekend regional, expect a large drop-off in attendance on Sunday and plan things accordingly.
8. It's nice to tell people the name of a bar or restaurant where those who arrive on Friday night can plan to meet.