Everybody has a different wave pattern and growth pattern. It's hard to make someones' hair look like some body else without styling it because of that. But what I was speaking of earlier is if you're wanting to go all natural and not do anything with it, hair health is directly related to how much sebum is in your hair, along with how you take care of it, and your diet.
If your hair is curly and you want it to be straight, you'll need to use tools. However, if it's healthy, it'll USUALLY look good all natural as long as it's cut to look good all natural.
But before I could give you advice I'd have to see it in person.