Apply a degreasing concrete cleaning solution to the floor with a heavy-duty mop, then rinse the concrete thoroughly with a garden hose. Allow it to dry completely.
Sand any rough areas with fine-grit sandpaper and remove any stuck-on dirt or other residues. Rinse the concrete down again and allow it to dry.
Apply pre-mixed concrete patch mix to any cracks, holes, or pocked areas and allow it to set up completely.
Tape off a grid pattern on your floor, using painter's tape.
Pour the paint into a plastic paint pan. Apply a coat of the paint as you move from one side of the concrete area to the other with a long-handled paint roller. Let this coat dry for one to two hours, then apply a second coat of paint. Allow the paint to dry overnight.
Peel up the painter's tape carefully, pulling at a 45-degree angle, to leave cleanly finished edges, which add authenticity to your new faux tile look.