It's "sticky" and can pull itself off the wall. Don't try to do too large an area with each roller-full, and don't try to touch it up or roll back into half-dry areas.

Feather it out nicely and don't stop until you are done.

If you have to stop in the middle of a wall, let it dry completely before you continue.

Don't look back either, because it can look really bad when it's not-quite dry. Let it dry completely before you decide if it needs touch-ups.

1/2 inch as all you need,3/4 is too big