I haven't driven lead, but I've done follow 1 and wheel car. My husband has driven lead.
Pointers for lead
Know the course - you don't want to be the lead car that goes in the wrong direction... (this has happened at one or two races around here - with guys off the front, oops - now technically its the responsibility of the rider to know the course and to not blindly follow the lead car, but still....)
If its the same as around here, you'll also be responsible for radioing ahead to the corners to let them know that you are coming, so you'll want to have a good landmarks in mind to use to know when to call it in. Be sure to call ahead giving the corner marshalls enough time to stop traffic. It's also helpful for the corner to know if there is a break and how much time between the break and main field (or break, chase, main field, etc) so that they know how long they should keep the corner closed. You should be in contact with the follow car, who will be giving you as much information as possible about what is going on behind you. Your life will easier if you can get someone else to come along in the car to work the radio, so that you can concentrate on driving.
The only other thing I can think of is be careful to get ahead by a pretty good distance before you start a descent. Racers can really pick up good speed going downhill and its likely that they can corner faster than you can. You don't want the pack catching up to you on a descent, so make sure to give yourself a bit more space before starting down a hill.