Stick pieces of masking tape to the floor around each side of the spindle's base. Stick pieces of masking tape to the underside of the spindle's handrail. Cut the pieces of tape with a utility knife or tear it by hand.
Scuff the spindle with a piece of 150-grit sandpaper to allow for more surface area paint adhesion. If the surface has never been painted then sand any rough spots on the spindle. Wipe away all dust with a tack cloth.
Pour primer paint into the hand-held paint holder. Use a metal primer for metal spindles and a wood primer for wood spindles.
Dip a paintbrush into the primer and brush the odd angled areas of the spindle first and then the flat surfaces. Roll over the entire spindle with a mini roller to roll out all brush marks. Allow the primer to dry for 24 hours. Lightly sand the primer coat and then apply the exterior finish coat of paint the same way the primer was applied.