STEP-BY-STEP
STEP 1
Prep the floor. For the wood floor shown in this sequence, that would mean stripping it of wax if necessary, doing repairs, filling large cracks, cleaning, and caulking.
Assuming the floor is sound, go on to power-sand the wood.
Then sponge-wash the floor with a degreaser such as Spic and Span or TSP; dry with absorbent towels and let the floor air-dry thoroughly. Next, use a primer if you have concerns about adhesion, or to lay down a dark undercoat for a deep-tone finish color.
STEP 2
If the ground (base) coat is not wall to wall, use painter's blue tape and a measuring tool or chalkline to mark the area; your design may have more than one ground color. Use a roller for efficiency, then immediately brush out the wet paint for a traditional finish.
Over wood, your best bet is an interior alkyd, applied in two coats. Oil-based marine and deck paints are tough, but are glossy and high in VOCs; they will smell for weeks. Milk paint, either one casein-based or in a modern formulation, lends earthy color and a matte finish perfect for old houses, but it will need a top coat for protection.
STEP 3
Once the base coat is thoroughly dry, you'll mark out the rest of the design, including borders or striping, diamond patterns, a checkerboard, etc. Scaling from your drawing, measure and lay out the design, using a chalk line. Snap straight lines. Mark edges and stripes in painter’s blue masking tape.
Because you can’t paint adjacent to a section that’s still wet, carefully plan your paint-decorating sessions in advance. Have an escape plan: don't paint yourself into a corner surrounded by wet paint.
STEP 4
Paint larger areas first, followed by striping and borders. Then do any stencil painting. Freehand work comes last. Freehand painting over a stenciled design will make the work appear to be entirely hand-painted—that's a 19th-century paint-decorators’ trick.
STEP 5
To protect the design from wear, you may want to apply a clear finish. Once the paint is thoroughly dry, apply two or three thin coats of a compatible polyurethane, according to label directions. Use a gloss finish for best adhesion; the last coat can be a matte-finish urethane, if your preference is a low sheen.