GET OUT WHILE YOU STILL CAN !
Mark... I judged car/truck shows for over 10 years at a very well known venue. Its a very unappreciated position. Theres a reason I no longer do it. However, with that said ITS ALL ABOUT THE KIDS..... right ?
So depending on your "entry fee" and anticipated car count you should gather donations and sponsors from local companies as mentioned. We used to use Summit Racing for "Goodie Bags" and add cool stuff from local vendors etc. A 50/50 raffle also helps with proceeds.
As far as judging...... you will NEVER please everyone. Depending on funding I would suggest the top XX picks. This can easily be done by walking around. You can tell if a car has "IT" by walking by. A closer look will confirm or deny you decision. You can also add BEST OFs.... (ie Interior, Paint etc).
Now for the guys like JayR mentioned we used to have an extra area designated for "Elite Judging". This was an extra $5 fee and was done in a "Drive up" judging format. For those interested, they would be told a set time to get in 2 lanes. A team of 5 judges were assigned "areas of interest" and given 30-60 seconds per car to judge (ie one judge just looked at paint/body, another just at the engine compartment, one just interior, one undercarriage, and the other "overall"). Looking at only one area that judge was able to compare just that one area to all the others. They collaborated with a 6th judge that noted the scores and kept track of totals. While one lane was being judged the other had a chance to dust or do last minute cleaning before they were judged. So one lane at a time alternated untill the lanes were closed. We could judge 300 cars in a 2-3 hours.
Call me if you want more details.