I tell you what I do. I always use 'silk' paint for ceinlings. It gives a shiny look as against a flat look a 'matt' paint will give you. So what you ask. Well the main reason I use silk is because it reflects the light so much more. Turn the light on and it looks like you have a brighter bulb in!
There are special paints for bathrooms and kitchens so we'll use the lounge as an example. Remove all cobwebs. You don't need to wash the ceiling at all. BUT if it is badly smoke stained, you will need a special paint that will cover that so that it won't bleed through,
Okay, after making sure there are no cobwebs, use a matt paint for the first coat.
Whatever way you do it, follow these steps. (If you want a silk 'shiny' finish like I have mentioned above) After removing all thecobwebs, paint the ceiling with matt emulsion paint for the first coat. For the second coat use silk emulsion. All done!
Obviously if you want a matt finish use a silk emulsion for the first coat and a matt for the second.
Why use 2 different paints? Because that way you can see perfectly where you are going and you cannot miss any bits.
Simple when you think about it! Good luck and use a roller. However some people cannot get on with a roller. In that case use a good quality paint pad.