I want to increase my Verticle jump about 8-12 inches … What can I doo????
You can always join the club of about 30 million other children who want to increase your vertical jump of about 8-12 inches. I understand that the next meeting is this Thursday. Normally meet on Tuesdays, but was changed to Thursday this week for the July 4 holiday … you get better at jumping the same way it would get better at anything … out and do it. Get a jump rope and good use of IT. This will help strengthen your legs and ankles, as well as increase endurance and coordination. Stand under a basket and, with arms raised, jumps up and down about 25 representatives at a time … (I used to do fifty, but I realize children are not as hard today as we were back then, lol 
) Then relax by shooting around or working on other aspects of your game … then return to blow the representatives … (The reason to do this under a basket is for you can measure their progress, as more and more toward the edge). If that sounds too difficult for you, then find another target … outside the "performance improvement" drugs, no way to do what you want to do, apart from a lot of hard work … unless you are going through a growth acceleration, in which case you may not need 8-12 inches … Good luck
Track & Field Training : How to Increase Your Vertical Leap