Begin by cleaning the Formica item with an ammonia-based cleanser and letting it dry thoroughly. Lightly sand and tape off areas you do not wish to paint. Prime and let dry, then sand the item again. Apply at least two coats, allowing each to dry thoroughly.
To protect the item, apply a coat of polyurethane after the paint has dried. Always ensure adequate ventilation when painting indoors. Use 150-grit sandpaper and choose a 100% acrylic primer. Allow about three weeks for the item to cure after sealing. Once complete, treat the surface carefully and use non-abrasive cleaners. If you do not like the final result, sand and restart the process.