Choose the correct string type for classical guitar: nylon or fluorocarbon trebles, and nylon or silver-plated copper basses
Remove the old strings one at a time or all at once
Clean the fretboard, bridge, and headstock
Insert the new string through the bridge tie block
Loop and secure the string with a proper tie knot
Thread the other end through the tuning post hole
Leave enough slack for several wraps
Wind the string neatly toward the center of the headstock
Keep tension while winding to prevent slipping
Tune the string gradually to pitch
Stretch the string gently by hand
Retune until stable
Repeat for all six strings
Trim excess string ends after tuning
Check string action, intonation, and tuning stability