Never put your cooked meat (or anything else that you are going to eat) back onto the same platter where you had your uncooked meat. The juices in the uncooked meat are not safe to eat. Have a separate platter waiting for the cooked items. Also don’t make any sauces or gravies out of the uncooked meat juices. See Meat Safety Tips
Know the difference between Direct vs Indirect Cooking and when to use each of these methods, with which foods.
To avoid burning, or under-cooking chicken (which is responsible for lots of picnic food poisoning) your best bet is to Cook Your Chicken in the Oven first and then finish it on the grill.
Here’s some more info on how to avoid illness by Boiling or Baking Chicken First before it’s finished on the barbecue. This site also gives some tips on when and how to use marinades, rubs and sauces on your chicken.
If you are making kabobs, it is best to grill up skewers of vegetables separately from your meat skewers. This is because it takes the meat longer to cook than the veggies, and your veggies will burn before your meat is cooked thoroughly. Also, leave a tiny bit of room between your pieces, whether it’s a veggie skewer or a meat skewer, so that the pieces don’t touch each other. This will allow the parts in the middle to cook evenly and completely. Here’s a recipe that shows you how to make Chicken Kabobs and Vegetable Kabobs Separately
Here’s some info about Cooking Potatoes on the Grill with several different methods and tips.
Be safe! Here are some Barbecuing Safety Tips. Not mentioned on this list are: keep your hair tied up and out of your face, keep your sleeves and apron and apron ties secured, keep children and pets and drunks away from the grill, make sure your grill is situated on a flat, firm level surface.
Invest in a good Meat Thermometer
Clean your grill regularly and properly. Here’s a How To Guide for Cleaning Grills