Paint the edges, corners, and around trim first using a 2-inch angled brush. Only cut in one wall at a time; you want to roll your main area while the edges are still wet to avoid "picture framing" (visible lines between the brushed and rolled areas). Dip the roller into the tray or bucket screen.
Use a work light at a side angle to spot any "holidays" (missed spots) or drips before the paint dries. How to roll a wall like a pro
Lift the roller, move over half a roller-width, and repeat until the entire section is smoothed out. Paint the edges, corners, and around trim first
Let the paint do the work. Pressing too hard creates "fingers" (beads of paint) at the edges of the roller. Use a work light at a side angle
To get a professional, seamless finish on your walls, follow this guide to technique and execution.