Anyone can load a roller and slap paint on a wall. The difference between that and a finish you are pleased with is almost entirely in the boring half hour before the lid comes off the tin.
Prepare the surface
Wash off cooking grease and finger marks with sugar soap, especially around switches and the kitchen. Fill cracks and old screw holes, let the filler dry properly, then sand smooth and dust off. Skip this and every flaw shows up worse under fresh paint.
Protect and mask
Five minutes of masking saves an hour of scrubbing later. Run low-tack tape along skirting and around sockets, and lay a proper dust sheet rather than newspaper, which sticks to wet drips and tears.
- Cut in the edges with a brush before you roll.
- Work in metre-square sections so the edges stay wet.
- Lay the paint on, then lightly roll back over without reloading to even it out.
Two thin coats beat one thick one
It is tempting to bury the old colour in a single heavy coat, but that sags and dries patchy. Two thin coats, with a few hours between, give a deeper, more even finish that does not need a third.
Clean up while it is wet
Pull the masking tape off while the final coat is still slightly tacky for a crisp line. Wash brushes and rollers straight away, or wrap them tightly in a bag if you are stopping for lunch. A roller left to skin over is a roller in the bin.