The thinnest string is string number one. It is the note E.

The thickest string is string number six. It is also the note E, but two octaves lower than string 1.

There are many types of tuners you can purchase to help get your strings in tune. You need to have a reference point to make sure the E string is tuned at least close to an actual E, by using a piano, guitar tuner, or listening to the pitch of my guitar in this video.

Once that is established, this traditional method of tuning will become second nature to you.

First Chords Video