Proper diet and exercise.
1) Eat more steam food, lean meat, lean protein, vegies and fruits
2) Cut out the junk food, soda drinks and snacks. Get rid of the junk food from the cupboards! Eat cashew / almond nuts instead.
3) drink plenty of water / green tea
4) Exercise - look at combining weights and cardio into your program. you can look at alternating upper and lower body exercises without rest, say bicep curls, then lunges , rest and repeat. With cardio, try sprinting 100m, jog 100m and repeat.
Here's a review link to Burn the Fat Feed The Muscle
5) Have 5-6 healthy meals a day(1 plate portions) to keep your body satisfied
6) if you have cravings drink water or eat fruits
here's a blog on understanding diet and exercise
Alternatively, try Fat Loss for Idiots
7) have an action plan for long term goals, start off with small goals and increase it gradually over time. And you will see in your size drop.
8) form a support group. Make yourself accountable to someone like your parents/relatives/friends/partners. Best yet, get them to participate in a healthy lifestyle.
Good luck