First, use a paint brush to “cut in” 2- to 3-inch bands around the edges, corners and frames of a room.When cutting in, you can try to do the entire room at one time. However, your border areas will probably dry before you overlap them. ...Fit a roller cover onto your paint roller.Pour the primer paint into a paint tray.Dip your roller into the paint, making sure it’s completely covered. Pass the paint roller over the ridged area of the paint tray a few times to remove excess paint.Start painting the primer in 3- by 3-foot sections. With a fully loaded paint roller, work top to bottom, rolling back and forth across the wall in a series of ...Roll in one section at a time, moving from top to bottom and from one side of the wall to the other.Reload your roller and paint the next section, covering only as much as you can finish while the primer is still wet. Always overlap areas of wet primer.