I find the statement "abs are made in the kitchen" to be more and more true the more I learn about it.
I've seen studies estimate that diet makes up about 75% of our physique, while, exercise makes up the rest. Can you get skinny just by eating healthy? Yes! Absolutely. Will you have strength or endurance? No, but this is an amazing start.
The average body fat percentage in which the ab muscles become visible is about 12%. This means you have to lose the fat covering them first! No number of crunches or lame ab workouts are going to get you there.
Start with your diet and clean it up first. It makes the rest a lot easier!