What is the best way to slim your tummy down after you have a baby, if you are not doing breastfeeding?

Depends. If you are in your early 20's you should bounce back quickly. If you are around 40 then it is going to take dieting: low carbs and high protein dieting. You also need to add cardio 4-5 times a week to help speed the process: running, elliptical, or treadmill. Also add some abdominal exercises such as situps, crunches. You can use a basketball and do situps with twists to the sides.