As a few have mentioned, it's down to practice mainly, I think I got to 35 events or thereabouts last year, it doesn't have to be expensive either, the following are
free at Castle Combe this year...
Saturday, March 08, 2008 - Porsche Club Day
Saturday, March 29, 2008 - Great Western Sprint
Saturday, April 12, 2008 - Alfaholics Track Day
Saturday, April 26, 2008 - Porsche Club Day
Saturday, May 24, 2008 - Lotus Club Day
Saturday, June 28, 2008 - Bristol Motor Club Sprint
Saturday, July 26, 2008 - VW Audi Track Day
Saturday, August 09, 2008 - Bristol Pegasus Motor Club Trackday
Saturday, October 11, 2008 - Audi Club Track Day
Saturday, October 18, 2008 - Bristol Pegasus Motor Club Sprint
Saturday, October 25, 2008 - Stroke Association Rally
Saturday, November 01, 2008 - Porsche Club Day
I will probably get to 2/3s of those this year, did many of them last year as well, just turn up and wander around the track, there are rarely more than 10/15 spectators to get in your way. You will be amazed at some of the toys that come out to play at some of these low-key events, the Porsche Club days are always immense...
http://chrisharrison.smugmug.com/gallery/2619859