Some Great Points from above worth highlighting/expanding:
Enjoy the time with your child, their team-mates and their families. Look for something good/especially enjoyable about each one. Have fun! It goes fast, you'll blink and your youngest will be U18 and you'll be in your last season...
Tournaments are often the first place Brand New refs see any game time, there is often Ref mentoring going on... be VERY gentle with these Refs in training and young Refs. We need them! If your team scores more goals, any poor calls the refs make won't matter in the end. Oh, and many of these young refs will be on the pitch in next weekend's Soccer Tournament - "we are them and they are us."
Staying warm and dry can be as big a challenge as staying cool. Be prepared for both. You may find that in one tournament you have memories of a sudden soaking and a sunburn. Canopies can solve for both.
Hydration, hydration, hydration - if its hot, ice chips and an ice shaver with a splash of 100% juice can be a fun way to hydrate when the kids can't seem to stomach another bottle of water. A sport drink post game for older/bigger kids is ok - but the electrolyte strength is often too strong for smaller bodies and should be minimized (some is ok - just not too much).
Post Game replinishment - Chocolate Milk is an awesome option (within 30 minutes post game) just be sure that the ice chest is cold enough to keep the milk safe or spend a little more and buy shelf stable chocolate milk that doesn't need to be refrigerated.
http://www.webmd.com/fitness-exercise/news/20100604/chocolate-milk-refuels-muscles-after-workout If you have healthy snacks and mini-meals readily available, and if junk food is not, its amazing that the players will snack on healthy options and be really happy about it... colorful veggies and fruit served as finger foods (orange slices, regular or frozen grapes, melon, bananas, apple slices) nuts (or maybe trail mix), dried fruit (raisins, apricots, pears), mini-sandwiches on whole wheat or bagels or pita bread, cream cheese, nut butters, lean meats, graham crackers, granola bars (although not the fakey candy bar type). Mix it up over the tournament days and you'll be a big hit. Parking away form the tournament villages has helped us avoic super greasy/super sugary foods that are usually available for purchase.
Oh yeah, and did I say enjoy every minute.. it goes fast.