There are many different paints, stains, and varnishes that are available today and this can make choosing paint a headache for anybody that has no idea what they are looking for. Paint falls into two main categories, oil based and water based. Varnishes and stains also fall under the same categories.
Oil based paints have a gloss, semi gloss, or matte finish. Oil based paint happens to wear well and makes for a good cleaning surface. Oil paint is good to use on doors, windows, or anywhere that needs a protection finish. If you need a good washable surface you can also use oil based paint on ceilings and also on walls, like painting materials usually. It is never a good idea to paint over top of wallpaper because it makes it harder to remove from the wall.
When painting with a water based paint it is so much easier to work with and the tools used can be washed with water, which is similar to paint brushes to most people. When painting your ceilings or walls water based paint is a good choice and also good for textured surfaced outside.
When painting any new surface it is best to use a primer. By doing this you will prevent any paint from being absorbed. Also by doing this it gives the paint something to stick to. The primer the you choose should be manufactured by the same company. Also you can use a water based primer for an oil based top coat but it is not a great idea to use a oil based primer for a water based paint. The number of coats the you will need depends on how porous the surface is, and the thickness of the paint you are applying, like painting tools usually. The overall quality of the paint has a big factor too.
I made the mistake once on not using a primer and it took me like 6 coats of paint. Its so important to get the right primer