In this day and age there are so many different paints to choose from that anybody that only slightly know what to choose can walk away with a headache. 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. It wears well and it provides an easy clean 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 paint brushes usually. Always remember that if you paint over wall paper it will make it a lot harder to remove in the long run.
Water based paint is much easier to work with this is because the brushes and all painting tools can be cleaned using only water, which is similar to painted surfaces to most people. When painting your ceilings or walls water based paint is a good choice and also good for textured surfaced outside.
On any new surface it is a good idea to use an undercoat or 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 or the under coat that you use should be from the same manufacture. For a hint you can use water based primer for oil paint but you can’t use an oil based primer for 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.