Loosen each string until it is slack
Remove the string from the tuning post
Remove the string from the bridge
Clean the fretboard and guitar body
Insert the new string into the bridge
Thread the string through the tuning post
Leave a little slack for winding
Wind the string around the post neatly
Tune the string up to pitch
Repeat for each string
Stretch each string gently
Retune all strings
Trim the excess string ends