Have a look at the following site concerning HIIT (High Intense Interval Training), i've found through past experience that interval training, and different versions of it, is the most effective way to burn fat.
You can start it easy and work yourself up each week/month, its all up to you. For instance, i started off sprinting for 20secs then jogging for 40 and repeating.. now i'm up to spring for 30 secs and jogging for 30 secs, on certain days i take it on an uphill slope (really drains the energy!).
http://www.musclemedia.com/training/hiit.asp
I hope this helps, i know it helped me improve my sprinting and endurance and also lose weight.