Core is also important for better looking body but we can't perform core workout daily as it put lot of stress on abdominal. Technique is very important otherwise you could hurt your hernia.
Start with knee hangs because they are best for your lower abdominal. Try to involve your core instead of your hips while doing the exercise.
The next exercise is reverse crunch that should be done on a normal bench but you can also do it on decline bench. The angle is very important in this workout as it should not be too steeper otherwise it will be difficult for you to perform the exercise.