my best advice is to keep warm, and maybe light light sparring just to keep you on top. If u rest and cool down, ur body will lose all the advantages from ur pre-tourni warm ups. I find it good to have a partner. Keep stretching, give each other little tips to remember, drink very small amount of water(a few sips at a time), eat light snacks, you don't wanna fill ur tummy with water or food(not fun during a match). Really tho focus on staying warm and keeping ur mind on the game. Once u start to rest ur body goes in to "recover mood" and i find u can't really compete at ur max. That being all said, my buddy likes to go smoke a phatty b4 each match and chill out. Seems to really work for him so i guess everyone has their own pre fight thing