Roller marks — those streaky tramlines and patchy bits — nearly always come down to technique, not the paint. Sort these four things and they vanish.
Keep a wet edge. This is the big one. Work in manageable sections of roughly a metre square and always roll into the wet paint you've just laid, never onto an area that's started to dry. If you let an edge tack off and then go back over it, you get a visible lap mark. Don't stop halfway across a wall to make a brew — finish the wall, then break.
Don't overspread. People try to stretch a single load too far, then press harder to get coverage, which leaves thin streaky patches. Load the roller properly, lay it on, then lighten the pressure on the final passes to even it out. Two thinner coats beat one thrashed-out coat every time.
Use the right nap. A short-pile microfibre or 9-12mm woven roller suits smooth plaster. Go too cheap and a foam or shedding roller leaves a stippled, uneven texture. A decent woven sleeve is worth the few extra quid.
Lay off in one direction. After loading and spreading, finish each section with light vertical strokes top to bottom, all going the same way. This blends the lap lines.
Paint choice helps too. A proper trade or premium emulsion has a longer open time, so the wet edge stays workable longer. Dulux Trade Vinyl Matt, Crown Trade, and Little Greene Intelligent Matt all flow and level beautifully. Forget cheap contract matt — it grabs fast and shows every join.
Colour-wise, deep or strong shades like Farrow & Ball Hague Blue or Down Pipe are less forgiving and show roller texture more than soft mid-tones such as Cornforth White or Skimming Stone, so take extra care with the dark ones.
Last tip: roll in good, even light and step back regularly to catch misses while they're still wet enough to fix.