Getting started

Honestly, diet is the best place. Make sure you're sticking to your calorie count for the day, and be very honest with your tracker.
Maybe later, when you're on a fitness roll then add in exercise. Also, I've heard from dozens of people that the "Exercise" portion of MyFitnessPal and actual cardio gym machines is being WAY too generous with the calorie burn estimate so don't even use it unless you want to sabotage your results.