OK, you've got your helmet and googles, riding boots, and good riding pants and jerseys. What more could you need?
Well, there are several more pieces of body armor available to provide additional protection for when you and your ride part company. Let's face it: anytime there is a contest between your soft body parts and hard rocks, pavement, or even the ground, your body parts are going to come in second place, and that is NOT a good place to be in that situation! Even landing on soft sand or grass can deliver nasty bruises and abrasions. A fellow scoutmaster once told the boys second place was first loser, and that certainly would be applicable in this situation.
Gloves are kind of a no-brainer for most off road riding. You might get away with wearing some heavy leather work gloves or even truck driver's driving gloves but actual off road riding gloves will be more comfortable and better protect your hands. Off road gloves are usually fairly soft and flexible so they are comfortable and leave you with the good flexibility and dexterity you need to manage the controls while also having special pads added to protect the exposed back side of your fingers and hands from unwanted impacts. Work gloves tend to be bulky and often have fat seams that can cause sores and blisters. The usually don't breathe very well and your hands will get hot and sweaty. For cold days, wear Wind Chill gloves or add glove liners to keep your hands warmer. Ski gloves are certainly warm, but usually are too bulky to handle the controls safely. Riding gloves are designed to fit comfortably, allowing you to grip the handlebars securely without seams hurting your hands. They have vented backs with plastic ribs to protect your fingers and the back of hour hands from moderate impacts.
Kidney belt would be next my on my list. This is an elastic band about 8" wide you wrap around your midsection. As indicated my its name, it covers your kidneys. Kidney belts usually have some reinforced bands to give extra protection to your body and your organs but they also provide extra back support that helps you maintain a good riding posture and minimizes muscle fatigue that leads to an aching back. Once you've worn a kidney belt you will greatly appreciate the extra support it gives and will feel somewhat undressed without one. Kidney belts also have the advantage of holding and supporting your abdomen. The heavy material along with the stiffeners provides a lot more support and protection than a shirt or jersey. I know riders who wear a chiropractic back brace in lieu of a kidney belt. It provides the same basic support but usually lacks the extra protection of the stiffeners in motorcycle kidney belts.
Then I would go for a chest protector. Chest protectors are made of sturdy plastic and basically surround your rib cage. It might better be called a torso protector because it protects your back as well as your chest. Some early models, often called Rock Jackets, pretty much ended there but modern versions usually include shoulder pads that cap your shoulders and pieces that even guard your collar bones Some riders prefer the rock jacket style because the extra collar bone and shoulder protection sometimes gets in the way of turning you head in a full face helmet, but I have found the slight inconvenience well worth the extra protection. That might be because my full face helmet once judo chopped my collar bone in an accident when I was wearing a rock jacket style chest protector. Chest protectors are well ventilated so there usually isn't very much of a heat penalty to pay when wearing them. I add a D-ring near the bottom of one side where I can attach a fireman's glove strap to keep track of my gloves when I stop along the trail. I also add a piece of velcro to the center and a matching piece to the bite valve on my Camelbak hydration pack so I can attach the bite valve where it easy to reach when needed and doesn't easily get snagged on bushes out on the trail.
Hip pads are usually part of your riding pants. Just remember to put them in each time you put on your pants. They are not bulky nor made of hard plastic, but the added padding goes a long way to cushioning your hip bones against hard obstacles.
Knee pad are, in my mind, almost mandatory. When riding an ATV or dirt bike your knees are often exposed to brush and your knees are very often the first part of your body to contact the ground in a get off, meaning you strike them at maximum velocity. Standard, simple knee pads are either strapped to your lower legs or tucked into pockets below the knees of your riding pants. They include a cup that covers you knee and a shin guard that extend down your leg into your riding boots. For even better protection go for professional knee braces. While they can be quite expensive, the extra protection they provide is well worth it. If you have had any previous knee injuries or weakness in your knees you should seriously consider getting knee braces. The are somewhat bulky but you get used to it. They not only cover you knees put also protect against over-extension and sideways displacement. Did you know it only takes about 12 lbs of pressure on the side of your knee to dislocate it? Compare that to the strength of your tibia (lower leg bone), which can typically withstand almost 2000 lbs downward force before snapping! Knee braces can help prevent sideways displacements, saving you from a very extensive and painful injury.
Elbow pads aren't as often seen on off road riders but I have found them to be very valuable. Your elbows, like your knees, tend to be among the first body parts to strike the ground during an accident. You know how it hurts when you bump your elbow! Like knee guards, elbow guards extend below the joint providing protection for your forearm as well. Coupled with the shoulder pads on a comprehensive chest protector, your arms are nearly covered completely, which can save you a lot of scrapes and abrasions and a lot of blood and pain. Some riders find them too warm on hot days, but I have always felt the extra protection was well worth the slight discomfort.
All in one body armor is available that combines kidney belt, elbow pads, and chest protector with a riding jersey so you can put it all on at once. It may make getting dressed and undressed a little easier but I prefer the added protection of individual pieces of armor. Slip on armor usually doesn't include the shoulder and collar bone guards found on state-of-the-art chest protectors, but it does cover chest, spine, elbows and shoulders.
Bandanas aren't exactly body armor, but they are a good thing to include in your riding outfit. I roll mine up, soak it with water, and tie it around my neck. That does two very valuable things: it protects my neck between my jersey and helmet from sunburn and it helps keep my cool as the water evaporates. There are some major blood vessels fairly close to the skin in your neck and the wet bandana helps cool your blood, which helps keep your whole body more comfortable in hot weather. Bandans can have other uses too. You can wear them bandit-style over your face to protect your nose and mouth from dust when riding exceedingly dusty trails or caught in a dust storm or to keep your face warmer when it turns cold. They can also be used for emergency slings and bandages so it is handy to have one conveniently tied around your neck if you or one of your riding buddies needs it.
In summary, you will find wearing full body armor will help you avoid a lot of injuries and is usually far more comfortable than ordinary boots, shirts, and jeans. Yes, you will have to put out a little investment, but I am sure you will find it is more than worth whatever it costs. Besides that it looks cool!