What is the best way to reinforce a creaky stair banister?

It is not difficult to effectively reinforce a creaky stair banister. First, if you have access to the banister from beneath, it is a good idea to drive a series of anchor screws into the base of the banister rails. Next, using good wood glue, determine the spots where the creakiness is the worst, and insert wood glue underneath the rail to set the banister. If needed, provided you have access from underneath, you can often fix the creakiness with a wooden dowel, a drill, and glue. Be sure to use good wood clamps to ensure that the creak doesn’t come back.