First you need the following items:
- a new set of strings
- a Tuner
- a wire cutter
Step 1: Open the pack of new strings. Notice that they have a size or gauge labelled on each sleeve. The biggest (thickest) string is the E string, and the next smaller is A, followed by D, and the thinnest is the G. Write the name of each string on the sleeve.
Step 2: Unpack the new D string and examine each end. One end will have a bead or loop, the other will have come thread covering the wires.
Step 3: Turn the tuning head on your bass to loosen the D string.
Step 4: Continue to loosen the D string until it comes off the tuning head. Notice how the string was inserted into the tuning head.
Step 5: Remove the string from the guitar by pulling it through the hole in the bridge. This may be on the front or rear of the bass body.
Step 6: Insert the new string in the same hole. Pull it all the way through until the ball or bead seats on the bridge.
Step 7: Extend the string up to the tuning head. Measure 4-5 inches past the tuner and cut the string.
Step 8: Insert the string into the tuning head the same way that the old string was there. Hold the string against the body and turn the tuner until the string becomes straight but still floppy.
Step 9: Remove the other 3 strings.
Step 10: Repeat steps 5-7 for each string.
Step 11: Gently increase the tension on each string until the strings are no longer resting on the neck.
Step 12: Using a tuner, tune all of the strings up to their correct note. Use the following sequence: D-A-G-E.
Step 13: Re-tune each string again. You will also have to tune them a few times until they “get used to” the tension.
That's it!