I would say that gloves are the second most important piece of motorcycle gear next to the helmet. The gloves are important for two reasons. One, they keep wind and debris off of your hands wile riding. Two, the hands are usually the first part of your body to hit the pavement. I would not recommend skimping on this piece of equipment because it provides both safety and comfort while riding.
The first thing to consider when buying a pair of gloves is their protection features. The most important feature is a good solid leather palm. What I would look for is a thick top grain cow hide or, even better, kangaroo leather palms with double stitching. The palms need to be specially protected because of the natural reaction to catch oneself when falling off a bike. Some gloves come with hard knuckle protection. This will better protect the hands in an accident as well as protect from stones and debris being kicked up from tires. Gauntlet style gloves also provide better protection and block the wind from entering the sleeve. There are many other safety features available such as 3rd and 4th finger bridge, Kevlar stitching, and additional sliders in fingers and cuffs zongshen parts
You should consider what kind of weather you will be riding in. For warmer weather, vents or mesh are definitely a must. Mesh is the best material for warm weather riding although it it substitutes protection for comfort. The best combination of protection and comfort in hot weather is perforated leather with knuckle vents. For rain riding, choose gloves with a waterproof liner inside of them eg. Drytech or Gortex. Waterproof gloves are also good for riding in cold weather because they are very effective in blocking out most air ventilation. Often times you will need to buy two sets of gloves to cover a full season.
A good fitting glove should be tight across the palm and not constricting in the fingers. The reason for the tightness in the palm is that the leather stretches. If the gloves are comfortable when you buy them they will be too big in a couple months. When trying out gloves test them on a nearby bike to make sure the palm does not bunch up. This will be very irritating after a few hours of riding. If you are buying gauntlet style gloves try them on with your jacket. Some jackets, particularly Icon, have extra wide cuffs which do not work well with gauntlet gloves.
There are many variables to consider when buying motorcycle gloves. Luckily, this is generally one of the less expensive items of gear you will be buying. With this in mind, if you discover after a month that you need something different in your gloves, it doesn't hurt too much to go out and buy a second pair.