First off I would like to say that gear is a personal choice. Since I am writing this up you get my thoughts on the matter. These comments do not necessarily reflect those of anyone else but me. To further that I would also like to suggest that you do not ride with objects in you pockets. Put little things like keys under your seat or in a tank bag. If you have to carry them in your pocket make sure they are in some place that you would not land on if you ever fell. It hurts, and getting all your keys recut because they ground down on the pavment is a pain, I know and have the fan shape burn on my leg to prove it.
Why oh why should you wear gear? It's hot in the summer, a pain to put on and take off, and it costs money that you could otherwise use to buy neat shiny things for you bike. But on the other hand it may save your life, stops you from becoming a vegetable, or greatly reduces the chances that you will need a skin graph after a session of asphalt surfing. Need some first hand experience of what a fall can do? Go to a road racing track and walk around the pits between races. Look at the leathers and helmets of the riders that went down. A good deal of those were in the corners and at a speed that you may very well find yourself riding at on the street. Now think of what the racer would have looked like if they were not wearing proper gear. It wouldn't be pretty. Buy the best gear you can afford, you get what you pay for. If you can't afford gear then how can you afford a motorcycle and insurance?
The great debate of textile versus leather. Both work well. It really does depend on what type of riding you will be doing. Textiles do not weight as much, are cooler in the summer, and warmer in the fall and spring, and are normally water proof (to a degree of course). Most now come with armour equivalent to their leather counterparts. They will crash once very well from all accounts, but after they will have to be replaced. Leather on the other hand will stand up better to slides along hard surfaces, and has a greater chance of being alright after a fall. I do not consider the mesh summer riding gear as textile gear. The mesh gear is better then a t-shirt but not by much. Riding around town they do offer some protection but they will shread into little pieces at speed
What is considered to be full gear? Well working from the bottom up, boots, pants, jacket, gloves, helmet. We will go through each of these sections with a short explanation of what to look for in each. The most important thing to consider however is how comfortable is it to wear? It is very important for the gear to be comfortable to you. This is because riding is suppose to be an enjoyable activity, not some trial to be endured, but also because you will be much more inclined to wear gear that is comfortable.
Boots
Boots should cover the ankle and be made of fairly tough material. Leather or synthetic material that looks like leather is most common. Road race style boots with full armouring do offer the best protection for your ankle and feet, but they do not bend very well. This means that walking any distance becomes a painful experience. Touring style boots offer good protection, and are much more comfortable to wear. Try to avoid steel toe boots, as they make shifting gears more of a challenge, and if the toe gets bent back in a crash you run the risk of amputating your toes. Boots should be high enough to allow pants/riding suit to be tucked inside. Closurers are usually better if on the inside of the leg. The heel and outside of the ankle are contact points in a crash and risk the boots closures being violently removed in a fall.
Pants
Pants should be either leather or synthetic materials designed for motorcycle use. Jeans will provide better protection then shorts but they will wear through in about 20 feet of sliding at 80kph. From persoanl experience they wear through in about 40 feet of sliding at 60 kph. Look for comfortable fit with much ventilation. Soft armour in the knees and hips is also a good thing, as these are likely to be impact points between yourself and the ground. Once again road race gear will provide the best protection, but is the most uncomfortable to wear.
Jackets
Same criteria goes for selecting a jacket as pants. They should be comfortable to wear, have much ventilation, several pockets for little things, and be made out of a material that will stand up to a fall. Metal buckles and studs should try to be avoided, and they are not the best things to fall on. You should look for something with soft armour that covers the major impact areas like shoulders and elbows.
Suits
For those of you who are getting into racing there are one piece suits available. These are armoured, and made of leather. I have seen a few synthetic ones out there but they are not very common. Suits should be tight. You do not want them moving around on you. They are very uncomfortable to wear for any length of time, and even the fully perforated ones are hot in the summer. They do offer about the best protection however. Two piece suits where the jacket and pants zip together are a more comfortable and practical option for street use, as they allow you to remove just your jacket.
Gloves
Gloves should cover your wrist, and be made out of a material that allows your fingers to bend comfortably. The gauntleted version that go over the jacket sleeve with some kind of wrist retention strap work well and offer better protection and comfort. Personally I like extra protection over the knuckles, either in the form of hard armour or soft. Its not uncommon to have two sets of gloves, one for cold weather, and one set for hot weather. Seams on the gloves are often on the outside, so they do not rub parts for your hands raw. This is one area where I have found road race stuff to be just as comfortable as touring equipment, more so in some cases as the road race gear allows you to feel more through the palm. There is however a large price difference.
Helmets
I personally like full face lids. Bugs and such don't smack me in the face when I'm riding at highway speeds. I also like the fact that if I ever go down my chin has a much better chance of staying where it is. Whatever style you choose, you should look for a SNELL approved lid. Go to this link for more information SNELL Fit is also very important when buying a lid. A good salesperson will take time to find the right fit for you. A new lid will be tight and squish your cheeks in, but it will loosen up over time as it brakes in. Not all helmets are created the same. Different manufactures have different shapes that they make the inner shell. This means you should try on many different helmets from different manufactures until you find one that fits you the best. Its your head, it doesn't heal real well like broken bones do. Spend the extra money and get the best you can afford.
Other Stuff
Whenever possible riding suits, gloves, and boots should be double or triple-stiched at points where separate panels are joined. Double stiching consists of two rows of thread; one hidden under where the leather is folded back and stiched again over it. Triple stiching typically has two rows of thread showing and one hidden. This reduces the chance of the gear coming apart in a long slide, as the stiches are worn away. The hidden "inside" row is protected by the other(s).
This is just a few other things that you should consider getting. Ear plugs are a must for any rider. They are cheap, and can be bought by the box at a local safety store. Wind noise in any helmet is very loud and can damage your hearing over time. Don't believe how loud it really is? Put in some ear plugs and go for a ride on the highway, and then do it again without. You will notice a big difference, with just wind noise not to mention things like exhaust noise and just general background noise. They come in all sorts of styles, so find ones that will work well for you.
Latex gloves are also a helpful thing to carry on you. For the cold mornings or evenings put them on and then put your riding gloves on overtop. They will keep you fingers much warmer by trapping a layer of air between the gloves and your skin. Sounds strange but I have used this trick a few times and it really does work.
For the road racer in you there are back protectors out there. They come in many forms but offer much better protection for your back then the soft ones found in most jackets. The kidney belts that may of them in corporate also help to reduce how quickly you tire over a long ride.
To finish up remember that whatever style of gear you decide to get make sure it is comfortable, fits well, and offers good protection. Buy the best gear you can afford and always wear it. Flip-flops, a t-shirt, shorts, and a skull cap may be the coolest, cheapest, and easiest option to buy and wear, but think of what would happen if you ever went down for whatever reason in them.
