Over the years I have tried many methods to tune my guitar. I have tried harmonics; tuning one string to another; and I have tried a few electronic tuners. In my experience none of these methods work reliably.
Maybe I am the stupid one who can't make it work. E.g. I've never successfully used an electronic tuner. I find the more sensitive they are the harder to use. And even when I think I've got it right I still don't trust it.
I used to use harmonics, until I saw this page and realised the method I was using was invalid. I could never make that 5th to 7th fret harmonic thing work; after reading the above page, now I know why.
This method does not work
I also learned from the above link that you can't tune your guitar to suit every note and chord.
In the end there is only one method I have discovered to work reliably: each string must be tuned to a reference note individually.
Fortunately in this day and age getting six reference tones is very easy. If you're at a gig you can listen to headphones to block out the ambient sound and hear the tone and guitar string properly. I use noise cancelling headphones and a little Casio keyboard for this purpose.
You can also use a mobile phone with a hands free set, although how you'd patch the guitar sound into that I'm not sure. Record the reference notes you need onto your phone.
One thing I've read time and time again is: always tune below the note and work up to the correct tone, or something in the machine head won't adjust right. In my opinion this is a myth; there is no difference which "side" you tune the note from, up or down.
Tuning each string to the exact same reference note (not an octave or harmonic) is called unison -- it's the only method I use.
The website I go to to tune my guitar is here:
Update:
I recommend to only use the free version of the above tuner. The 99c cent app version is crap because it's not really yours to keep even though you paid for it. It's yours but you need an active wi-fi connection and be signed into your amazon . com account to use it. So if you're on the road with no internet access you can't use it. It's total bullshit. Do not use!!!!! Waste of time.
