You'll hear alot of differing opinions on how to break in a glove. My son is 12 now, and (for his age) quite a serious ballplayer. His Tournament team won the state sectionals last year, and are hoping to go further still this year. In fact, we leave Monday on an 8 day trip to Aruba where his team will compete against Aruban and other Carribean teams, prior to the start of the Little League season. Less expensive gloves are typically easier to break in as they are made of cheaper leather. Some are even offered as "game ready". These can serve well for a season or two, but tend to deteriorate quickly, and lose their overall form. Rawlings has a good mid-level glove in their Gold Glove Series. Mizuno also has a decent mid range glove in their MVP series, as well as the Wilson 750/1000 or Louiville/TPX Omaha.
At 11 years old, stick to an 11 1/2 inch glove. My son has gloves of different sizes depending on whether he's pitching, playing SS or 3rd base. Outfielder's and pitchers tend to use gloves measuring 12-12 1/2 inches, with most infielders in the 11 to 11 1/2 range. A good 11 1/2 will give him enough flexibility to go from left field, to 2nd base, to the mound comfortably.
First rub the mitt with glove oil, which is readily available. We like to use sheep's lanolin early on in the "break-in" period, and then treat with oil 1-3 times per year.
This method has been sure fire for my son's very hard to break in Rawlings Pro Preffered and Heart of The Hide gloves: Rub liberally with sheep"s lanolin (available from most drug stores). Place a ball in the "pocket" of the glove and tie tightly using rope, string, gauze.....whatever. Then place the tied glove into a pillowcase, and put it in the dryer for an hour with no heat. After removing, work the glove vigorously opening and closing it repeatedly in an effort to soften up the leather and creat a natural seam where the glove closes. Then place the ball back in and tie -up over night. Repeat this procedure the next day and again leave over night. Remove the rope, lightly apply a last coat of lanolin (wiping off any excess), and then start playing catch. All the while kneading and working to glove to form the pocket further and coax it to close where you want it to.
Aside from the dryer technique (which has worked wonders), oil and tie, and continue over the course of a couiple of days to pound out the pocket and work the glove opened and closed repeatedly.