Always start with the first G string and change only one string at a time.
Lift the tailpiece to expose the strings (INSERT TAILPIECE TWO PIC)
Unwind the string from the tuner post using the tuner knob
Remove the loosened string from the tuner post using tweezers if necessary
Attach new string to the tailpiece using tweezers if necessary
Bring string up to the peghead measuring two tuner posts above the one you are changing for excess string
*this is the key to having enough excess string to wind around the tuner peg*
Trim the string
Using needle nose pliers, bend a 90 degree angle with the top one-quarter inch of the string
Insert end of string into hole of tuner peg orienting it so the end faces the edge of the peghead
Using the tuner knob, wind the string around the tuner post in a direction that keeps the string in the center of the peghead
Continue winding the string around the tuner post using the tuner knob (a string winder helps speed this up!)
Wind until fairly tight but not to pitch
Move to the next string starting at Step 3
For the Upper D and Upper A tuner posts, measure the excess string length in the following manner:
Attach new string to the tailpiece using tweezers if necessary
Bring new string up and measure to the tuner post
While still gripping the string at the tuner post, slide the string back two tuner posts. (See Measure Two Image Below) Using the tuner posts as a measurement guide for the excess string, (See Measure One Image Below) trim the string (See String Cut Image Below)
Follow Steps 7 through 11
Once all strings have been changed, tune the instrument. It’s often helpful to tune the string above the pitch, tune back down below pitch to stretch the string slightly before turning back up to pitch this helps move they string through the nut in both directions and minimizes the tendency for a new string to de-tune. Always tune a string up to pitch. If you overshoot the pitch, tune it back down below pitch and then try again to tune up to pitch.
It is a good practice to clean the slot in the nut out and use a small bit of lubricant like Vaseline to aid in moving the string back and forth.