Sand down all the surfaces of the table that you intend to paint with 100 grit sandpaper. There is no need to completely remove all the old paint or varnish so long as you achieve a smooth, even finish with the sanding.
Remove all the dust by wiping over the surface with a soft cloth.
Apply a thin coat of oil based primer to the table, using either a paintbrush or a paint roller. Allow the primer to dry completely. Follow manufacturer directions on the tin for the correct drying time of the primer.
Paint the table surface, using the foam roller, with a thin coat of latex paint in the color of your choice and allow it to dry for 24 hours before applying a second coat. If drying times between coats are given on the paint tin, follow those guidelines.
Allow the table to dry for at least two days before placing any items on the surface.