How do I caulk a bathtub without it looking messy?

Start by removing any old caulk completely using a caulk remover tool or utility knife, then clean the surface thoroughly with rubbing alcohol and let it dry. Apply painter's tape along both edges of the joint to create clean lines, leaving just the gap exposed. Fill the tub with water before caulking so the tub is weighted down, which prevents the caulk from cracking later when you use it. Apply the caulk in one smooth, steady bead by moving the gun at a consistent speed. Then wet your finger or use a caulk smoothing tool to press and smooth the bead in one continuous pass. Remove the tape immediately while the caulk is still wet, pulling it back at an angle for crisp edges.