You can use a simple webbing type strap available from car accessorie places, Kmart etc. The 1" ones work well.
It's just to stop the bonnet flying up and getting intimate with the windscreen if the latch fails so it doesn't have to hold the bonnet fully closed.
Loop it around a strong part of the car (a bracket etc) and through a strong part of the underside of the bonnet, adjust it down so you can just fit your hands under to loosen it later. MAKE SURE THE LOOSE END OR ANY OTHER PART CANNOT GET CAUGHT UP IN THE FAN, BELTS ETC
If in doubt get someone who knows what they're doing to do it.
Check all the fluids and have the brakes bled.
Inflate your tyres to around 40 psi (check with your tyre place for correct inflation).
A fire extinguisher is a good idea. Just make sure it is securely attached so you don't end up with it flying around the cabin in an accident.
I push it hard for a few laps and always give the car at least 1 lap to cool down. If you punish it, things will break. My stock brakes and pads don't show much wear after a track day. It's all about how you treat them.
It may sound like a bit of stuffing around to get the car ready but it's well worth it. Everyone who drives should get on a race track.
What do you drive?