The previous guitar tuning tip was about letting both strings ring as you tune. The next tip is related.
Remember that these tuning tips have been using the method of tuning the guitar to itself. In the example I’ve been using (tuning the D), it will be easy to accidentally let go of the A string. Do your best to keep the A string pushed down on the 5th fret.
Now, be sure you are holding the guitar properly (whether sitting or standing). After you pluck both strings, letting them ring:
Tip 3: Reach around the front of the guitar with your right hand.
Since your left hand is holding the A string down, your right is free after you pluck the strings. You will turn the farthest tuning peg on the top of the guitar head, connected to the D string.
Here’s a video explanation:
One of the other ways of tuning a guitar is by using harmonics. Here’s a simple explanation if you like. It’s a little more advanced. One advantage to this method is that no reaching is required.