Assess the area that gets oversprayed. Depending on the size, if it is not too much you might be able to remove it simply by using water and dish soap (if you are fast enough).
In case that does not work, try with a clay bar kit. Rub the bar over the affected area and it will pick up the paint.
If the damage is pretty big, clean up using solvents like acetone, xylene, or mineral spirits. Continue with remover. Finally, clean the surface with water and commercial detergent
Avoid overspray by completely masking all the areas you do not want to paint. Masking can be quite a hassle, but it could save you a lot of energy from having to scrub the coating off a surface.