If you've never overnighted on an ATV outing before, you're in for a real treat. It only takes a little planning and organization to insure you have a great time with your friends.
Before you go for a long weekend on your ATV, give your machine the once over and make sure it's in good shape for the ride. A little preventative maintenance will save you a large repair bill on your ATV when you check it often for little things like screws that need to be tightened, spark plugs, brakes in good order, chain lubed and other routine items.
Make sure you have a little tool box and a first aid kit with the basics on your ATV when you're riding. Having a few tools and an extra spark plug or two can save your entire trip.
Next, think about comfort when sleeping, bring a tent and a sleeping bag for yourself and a tarp will usually suffice nicely for your ATV and gear. Also, consider food and water. Water is a must when you're riding. Dehydration can make you ill and lead to fatigue which is one of the biggest causes of preventable accidents. A small cooler will protect your food from curious critters and don't forget your personal items such as your tooth brush and paste, wash rag, some towels, etc. You will need some cleaning items for keeping your camping area neat and tidy. Some of these items are a broom, some rags, dish pan, etc.
Last but certainly not least, bring a bag to put your trash and other refuse in. Remember, if you bring it in the ATV trails with you, bring it out and it will keep the trails beautiful for future generations to enjoy!