To caulk windows, start by cleaning the window frame and removing any old caulk. Use a caulk remover if necessary. Apply painter's tape around the edges for a clean line. Cut the caulk tube tip at a 45-degree angle, and apply the caulk in a steady, continuous bead. Smooth it with a caulk smoothing tool or your finger, then remove the tape and clean up any excess caulk.

Clean frame, remove old caulk, tape edges, apply caulk, smooth, and clean up.