Dont run too many barrel patterns from now until the fair, this will sour your horse and take away the fun from barrel racing for your horse, making him less likely to WANT to run well for you.
Since he is a barrel horse, and is likely used to working in a ring, take him on trail rides, only at a walk and jog (you dont want him tripping or stumbling and hurt himself before the fair!)
Stay light on his face, turn mostly with your seat and your legs--too much face pressure will cause him to shoulder in and cut the barrel too tight and thus knocking it over.
Pocket your barrel--come in a bit wider so your horse is able to cut around the back half of the barrel tightly and line up for the next barrel better.
STRAIGHT LINES---from barrel to barrel, your lines inbetween should be as straight as possible---the shortest distance from A- to B is a straight line :D And it really is.
Keep pushing all the way home, right until the timer line, don't let your horse slack off 1/2 way home it will add time to your run---your horse (hopefully) knows how to stop well, and will do so when asked to---you only need 25 feet to stop a full out horse, remember if you aren't using a chute to enter the ring, curve along the fence to avoid running into the gate at the end of your run---much safer for everyone.
Before your class starts, warm up by jogging (first on loose rein, then once your horse is warm, collect him and ask for a slower jog to warm up his muscles more)---lope on both leads, get him listening to you, tuned in to your commands and not what is going on around you---transition up and down through gaits, including lope to stop....only warm up until your horse's neck is warm to the touch---after this, keep him walking around until your run--dont just stand in the holding pen (which will allow his muscles time to stiffen up and become cold again)---if you are near the end of your class, about 1/2 way through the class do a few jogging circles by your trailer to make sure he stays warmed up and supple---
Hope I helped :)
Good Luck!
Turn N Burn!!!
BB