Vacuum and mop the floors and let them dry. Go over the entire floor surface lightly with the wire brush to scuff the surface. Vacuum and mop once more, being thorough---remember, anything left on the floor at this stage stays on the floor.
Paint the entire floor with the oil-based primer, using long, even strokes. A paint roller works fine, but can stress the paint and cause bubbles, so unless you have a back problem, use a paintbrush. Let dry according to the primer manufacturer's instructed drying time.
Pencil in any designs you are working into the floor.
Paint on a coat of the oil-based paint, using the same long, even strokes as you did with the primer. Leave to dry for four hours, then apply a second coat. Apply a third coat if you think the coverage warrants it. Let dry according to the paint manufacturer's instructions.
Paint on a coat of the clear urethane varnish with the paintbrush---check that the label specifies "non-yellowing" in the product description. Let dry, following the manufacturer's recommended drying time. Paint on two more coats, allowing the necessary drying time in between. Leave for two or three days before walking on the floor.