Mix fine sand in with your paint or sealant before applying it. Sand adds texture to the floor surface and make it less slippery. Use a fine-grain silica sand at about 1 pound per gallon for best results.
Place non-slip tape strips along the floor in high-traffic areas and near steps and entryways. The tape bonds to the concrete floor and has a coarse material on its face. This is the same type of tape used on boat docks. If your concrete floor is not painted or sealed, it should at least be primed before using.
Create a broom finish. After painting the concrete floor, simply take a broom -- preferably one you don't intend to use for sweeping -- and drag it over the wet floor. This will create ridges in the surface and a non-slip finish. You can overlay a broom finish by repainting the floor or applying a sealant then using the broom on the wet surface.