Finding a glove that best suits your needs is mostly based on how it feels to you. A glove that is flexible usually has soft leather and is easier to squeeze. Condition your glove with glove oil to make it more pliable and ready for action. Gloves with a deep pocket make it tough to turn a double play because the ball gets lost in the pocket. Second basemen usually have the smallest gloves of all the fielders while shortstops will have slightly bigger gloves than second basemen. A good baseball glove mainly has to feel right to you.
Refer to this glove sizing chart.
Persistent practice and repetitions are the best way to improve any aspect of your game, particularly fielding. There is no substitute for hard work and practice. Keep the following in mind when working on your skills for fielding:
When scooping balls out of the dirt, try to keep your glove down.
If you see the ball bounce, raise your glove with the ball
Provide cushion when scooping the ball so that it doesn't pop out.
If you are a first baseman, always expect a bad throw so you'll be ready for it.
Properly positioning prior to the pitcher throwing a pitch - position yourself as far back from the batter as you feel comfortable, but take into consideration how fast the batter will run to first base.
If you are playing third base when a double play situation arises, and a ground ball is hit toward the third base side, try to wait for the ball to get close enough to you before starting your movement towards second base.
If a runner on second is looking to steal third, make sure that you keep an eye on him. If he attempts to steal third, wait as long as you can to see if the batter at home plate hits the ball.
If a runner is rounding third base and heading home, and a ball is hit to the outfield, try to position yourself about 15 feet in from the baseline.
The best thing to do when you are playing catch or throwing to a base is always step toward your target. Accuracy can be more important than a strong arm.
Work on throwing some long tosses to make your arm stronger.
Getting on top of the ball, versus to the side, will help straighten your throws.
Do not let your arm drop to the side if you are throwing over the top.