Does anyone know if you can paint latex paint over enamel? Or is it you can paint enamel over latex? I cannot remember. One way you aren't suppose because it doesn't stay on good, because there's no bonding.
Since enamel is a very smooth paint you have to rough it up first by sanding it.
I run the batchmaking department for a large paint manufacture. The rule of thumb is that, given proper surface preparation, for exterior use you can apply quality latex paints over oil-based, but not the reverse. However, if you have many layers of oil based paint, stick to using oil on oil. For interior use, generally you can use one over the other. Some manufacturers of latex products will recommend a primer when going over oil-based paint.
From personal experience I know that latex does not bond well to enamel paint. You can sand the enamel-based surface lightly, or prime it with something like Benjamin Moore's "Fresh Start," and that will cedrtainly help, but the surface will still be prone to chipping, especially if it's in a high traffic area (like kitchen cupboard doors, for example).
Give the surface a light sand, make sure to wear mask so not to inhale the dust. Clean the surface from dust and dirt, coat it with a good quality primer, then paint away.