There are simple and complex variations of ab workouts. It would be best if you can find an ab workout that is created basically for beginners to advanced levels of fitness. The best ab workout should work on the main abdominal muscle groups, transversus abdominis, rectus abdominis and also the internal and external obliques.
Choose a workout that will target your hip flexors. When your ab workout involves the hip flexors you get to maintain the strength to your legs and the core is kept strong at the same time.