Over the years, I've done various kinds of plastic figures. Generally they paint up well. I've used acrylics, enamels and even oils.
Preparation is key. Be sure to wash the figures thoroughly in hot soapy water. I let them soak for 1/2 hour to remove all the mold release. Dry them thoroughly.
The main problem for me seems to be getting a good undercoat to give the color coat something to grab onto. One time-tested technique is to mix about a 1/3 - 1/2 portion of white glue (e.g. Elmers) into your primer. This helps the primer stick to the figure and provides "tooth" for the future coats of whatever paint you use. Be sure to let the primer dry thoroughly - I like to let it dry overnight. Then your painting should go smoothly.
Good luck.