Don't just walk the course, work it if you can. Be a corner worker at the most complex part of the course, or just the one you are having problems with. You will get to see all kinds of people go through and see up close what works and what doesn't.
Ride with an experience driver and/or have one drive with you the first time. Their input will be invaluble and you can eliminate a lot of the trial and error.
Bring a video camera and have yourself taped. This will show you your line a lot better than just trying to remember and you will see where you are losing time.
STAY OFF THE CLUTCH! You can't accelerate if you aren't in gear. Sounds simple, but at least for me it was very hard to overcome the urge to shift. Most autoX courses are 1st or 2nd gear courses all the way through in the SVTF. I use 1st 90% of the time, and only shift when I have a full second or two ahead of me where I would be banging off the limiter. Otherwise just leave it in gear and contcentrate on the course.
Be smooth and clean. Try no to make any jerky or quick imputs. Do your best to string the steering and pedal imputs into one long, continuous motion. This will signifigantly reduce understeer and keep you off the cones. You'll notice that the fastest driver's laps aren't really dramatic and showy, in fact they can look positively slow until they pull in an amazing time...
Try to line up chicanes and corners so that you go as straight as possible through them. You might want to swing a bit wide out of a turn so that you can take a set and be heading straight and fast through a series of corners instead of trying to take that first one as quick as possible and struggling to keep it on course through the rest of them.
I would personally leave the left foot braking until you have more experience. It takes a lot of concentration and finesse, especially when you are learning, and you are going to be busy enough with steering and the gas to worry about that just yet.
But really, don't work yourself up too much about it. The calmer you are and the more fun you are having, the better you will do. ENJOY!!