Easy way to stop some squeaky timber stairs. This tutorial shows marking the riser face on tread using a template, drilling pilot holes through tread, and screwing down into riser. If possible also screw up into riser from below, if no soffit under staircase. You may also want to tighten under the riser of lowest stair by wedging under riser with shim of wood and PVA, then chisel off surplus wedge when PVA is dry. These techniques are suitable for stairs that will be carpeted or filled/painted. Not suitable for stairs that will remain bare.