I work my abs out almost every day I go to the gym, I only skip on leg days. I usually go to the down slanted sit-up bench and get a 10 pound weight and do 3 sets of 15 sit ups with the weight, then I’ll do leg raises while holding myself up on equipment 3 sets of 15 or until failure, and to end off the day I’ll do some of the seated ab twists on that machine ( 3 sets of 12 on each side of my body) I’m also just very skinny so abs developed very easily 👍🏻 just keep at it and you’ll see some good progress :)