Ok this might take some time so bare with me.As a painting contractor going as green as posible I reconmend and use a latex (water base) paint. The difference between latex and oil base paints are quite simple. Oil base paints are solvent base wich requires thinners to break them down and/or clean up. They (solvent base) also have a much higher VOC content (fumes that are released into the air) wich makes them very stinky. They also turn yellow after a year wich will afect your color from holding its true color longer. The good thing is oil base paints have excelent bonding agents and good leveling (a smooth look).
A latext paint requires water to clean up and has a lower VOC content. They never yellow and now have good levaling. As far as bonding gose (sticking to the previously painted suface), latex sticks great to all latex surfaces but not good to a surface previously painted in a oil. So here is a simple way to avoid any problems. If your ceilings and walls are now a flat paint you are safe to repaint them with a latex paint but, if your walls, ceilings and/or trim are now a semi gloss you will need to prime them first with Zinsers' Bulls Eye 123 latex primer wich will stick to anything. If you know what your colors are try to have your primer tinted half formula to you finish paint color. If not tint the primer a off white. This will insure propper coverage wich might save you from applying a third coat.
So if fumes and the invioment are issues with you then a latex paint is your paint. If leveling (glassy look on your trim) and bonding are your issues than oil base is your paint.
What some of us do to avoid bonding problems is to paint your ceilings and walls with a latex flat and paint the trim with a oil base paint. You will have to thin any oil base paint before use.
Good luck and try to have fun doing your work.
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