How do you roll paint evenly?
Also asked, what causes roller marks when painting?
Each stroke of the roller transfers less paint to the wall than the last, which can leave visible roller strokes on the walls when you've finished. Bumps and ridges of thicker paint from the edge of the roller can mar the surface, and wet paint applied over dry paint leaves lingering roller marks.
Then, will streaks go away when paint dries?
You're more likely to get roller marks when painting a dark color on a light wall. When you notice holidays after the paint has dried, you can usually make them disappear by applying another coat after sanding lightly—if necessary—to remove drips and humps.
Rollers leave a texture or stipple effect that looks like a orange peel. That said by using a small nap roller like 3/8" or smaller will make the stipple smaller. And by adding a product such as Flotrol or BIM extender it will also help to limit the effect.