Best way to encourage good driving, is to go up to another driver who you had a good race with and thank them for the clean run. Generally they will start to do the same in the future. It's always fun to walk back to the pits talking with other drivers about the close racing.
Another good thing to do, is have your Race Director let lapped traffic know when the leaders are coming up behind them. We've taught this to our new drivers and since then, lapped traffic crashes have gone down significantly, leading to much closer races. And if the Director is on top of things, she can also point out the position battles (extremely useful for spectators). On any given club race, we get about 25-30 people stopping by to check out the action. They love it when they can follow the cars battling for position, especially when it's the leaders.
I've just gotten involved with mine this past spring, and we just finished our largest gathering for the state championships ever. And our race was on the same weekend of mod-nationals, so we were missing all of the Colorado drivers who normally come up!! Ways to do this, are contact every hobby shop within a days driving distance and ask them to post a flyer about your race. Most are more than happy to oblige. If your track does not have an on-site hobby shop, when you host a large race, try to bring one in. That way if people need to buy stuff they can. Since we do not even have a hobby shop in our town, we brought down Extreme RC from Billings. They did very well, selling many kits, along with tires. On the first day (we run electric day 1, gas day 2), he sold several 1/8th scale buggies and spent the day breaking in motors for the guys so they could run the next day. Also promote your race. Since we are a small town, our radio stations were more then happy to have our race organizer go on the air to talk about the weekend's racing. As a result... got a couple of new entries, many people checking out the hobby and asking questions. Also, if other tracks are within a few hours drive, work them on race schedules attempting to avoid as many conflicts as possible. That way you both can increase your attendence by going to each other's tracks.
Do a points series!! This will keep drivers coming back, because they don't want to drop in the standings by not showing up to a race.
Wow this is long, hope it helps though.
