Top fitness model Rob Riches has an incredible set of abs and he loves to do supersets to get his abs looking perfect. The key to a good set of abs is not the upper abs, which many have and easily can work out; what separates the ripped and toned from the average gym goers is the lower abs.
Get a nice set of lower abs you are GOLDEN!
To work the lower abs, Rob Riches likes to do rocky hip thrusts. Watch and notice how important doing proper form is with any exercise as Rob dictates below. You only have to extend the length of the muscle that is being contracted. A lot of people overextend themselves past the point of contraction, especially with abs, to the point where they injure other bodyparts, namely their lower back.
Be careful when doing abdominal exercises or any other exercise for that matter and always remember form is paramount in order to achieve optimal results.