How would you rate my hair? Any advice?

Pretty much what the title says. Now I think my hair is alright. Some people said it looks good this way and some said it doesn't.

Usually when I haven't applied any products to my hair it looks less voluminous. I have very straight and thin hair naturally.

Also I prefer a messy look like this but I am curious about what you guys think. Maybe some suggestions to other hairstyles even! Thanks for every piece of advice!!