First kickboxing tournament ?

i have my first kick boxing tournament in a weeks time and am looking for some advice on how to do well i am only just a white belt so not much experiance i spar in my cles and am below average and keep dropping my guard wich ends up with me taking crosses to the head.i will be competing in 1 minute rounds then continuos so any advice would be great not important but i stand at 5ft 9" and 17st 7pounds so quite a big guy not all fat.