Having fully covered everything below ceiling level which you do not wish to have painted… Make sure first of all that you have removed any loose pieces of paper from the ceiling, removed any blue tack, sellotape, chewing gum, dead flies and spiders, cobwebs, etc. etc; filled any holes, and given the ceiling a good wipe down with Sugar Soap. (This will remove grease and any residual chemicals such as cigarette smoke stuff).
Get a good, strong, large container or proper paint scuttle and pour your paint into it. I would suggest that it is not a good idea to use a silk or semi-gloss on a ceiling, because such finishes really do show up all your brush marks and any inconsistencies on the surface. So don’t use this finish unless you really are a good painter.
Using a large, fluffy roller on a pole, which should first of all be rinsed with warm water and allowed to more-or-less dry out (it will absorb your paint better this way), first of all load the roller so that it is good and ‘full’ of paint, then apply it to the ceiling, starting at one corner and working from one end of the room to the other. Employ a steady consistent action to move the roller back and forth.
Use more paint than you think is necessary and don’t let the roller dry out. If it starts to become hard work, you probably aren’t using enough paint.
(Use a matte finish emulsion – the best quality you can afford)
Go around the light fittings using a brush. If your roller won’t get right into the corners, use a brush here also. You can do this before you roller or after. Really it doesn’t matter. Many light fittings will unscrew from the base on the ceiling.
Don’t lose track of where you get to if you stop for coffee. White on clean white can be difficult. Then again, if you’re painting it, your ceiling probably isn’t too clean, so forget that bit.
Stand back when you think you’re done to make certain that you have covered it all. If you’re using an emulsion matte paint, you can go over bits you’ve missed, and it won’t show up when it’s dry.
Repeat the entire procedure if you purchased cheap rubbishy paint. (Save time – buy the good stuff in the first place!)
Clean up the roller by endless washing under a running tap, or if you’re rich, throw it away. Cleaning up rollers is a pain in the neck (so is painting ceilings – literally) but it can be done if you’re patient. Alternatively, wrap the painty roller in a couple of plastic bags if you need it later on for another area with the same color paint. Properly wrapped up it should keep fine for a few days.