First of all, pick the right team!  Just kidding, tailgating parties have more to do about the spirit and energy of the environment than who is playing.  Although, having a really good rivalry really doesn’t hurt.
When planning for the pickup truck tailgate party, be sure to keep simplicity in mind in all decisions.

The party supply checklist must include folding chairs, a charcoal grill, charcoal, lighter fluid, a lighter – make it two –, a large cooler, plenty of ice, bottle openers, bug spray and sunblock.
As a matter of fact, if you can devise a way to stretch a canvas to provide shade or protection from the elements, you will be a hit.
Make sure plates, cups and utensils are disposable.  Also be sure to bring several trash bags for clean-up and plenty of paper towels.  And, although not the most masculine item on the list, especially for testosterone driven sports, there must be a large container of baby wipes on hand.  These things are great for cleanup of surfaces and people without needing soap or water.  Another thing to consider, depending on the time of day, is lighting.  If anticipating a late game, bring torches, or better yet, LED camping lanterns – which won’t set the place on fire if someone trips over it.

Another good thing to bring is a credit card.  You just never know what else you may need, and cash is easily misplaced or lost.

To be sure everyone can find you at the designated tailgate location, a great idea is to make a large banner with a pre-determined odd color background so all of your guests will be able to easily spot you in the crowd.

Food needs to be simple finger food that will be easy and quick to cook or warm up.  Plates and forks do not accommodate well to spontaneous high-fives, so stick to small burgers, hotwings, ribs, you get the idea.  And bring plenty of munchies, or ask each of your guests to bring a bag of munchies.  This way, you’ll be less likely to run out.

Drinks are self explanatory, but be sure to include soda and water, especially if a particularly hot day, and also in consideration of the designated drivers.

For pre-game entertainment, a couple frisbees and a football to have on hand is a must.  The party guests will certainly provide the inspiration for the competitions.  Speaking of competition, offering a six-pack to the guest with the most enthusiastic game day wardrobe and make-up will surely provide it’s own entertainment.