Diet is extremely important. Cut out processed foods like cheese, pasta, bread, butter, salad dressings, sugar, desserts, etc. Rely on lean protein and fresh vegetables and fruits. Then exercise by running, jump roping, biking, skating, swimming for 30 minutes to an hour a day for cardio. Then, on top of that, each day work on one part of your body: torso, arms, legs, and an extra day for flexibility. For the torso, crunches are great. For the arms, use soup can as weights and lift them repeatedly in a curling motion and from your side until they are raised above your head.
For your legs, do squats against the wall. And for flexibility, do yoga through videos online like You tube ( suggest sun salutation for beginners). Let your body relax on the weekends but continue your diet during these days.
Best of Luck!