There’s an easy way to tune your cuatro. You’ll learn it here, by noticing where to put your fingers on the frets and how to get the right sound of each string.
First, you will get by reference the sound of the A string. Here’s a video with a 440Hz as reference:
After you have this reference, you can use this string to tune the other ones, first place your finger on the 5th fret to get the D note:
This note has to be the sound of the next string. Just move your peg until you get this sound on the next string.
After you get the right D note on the second one, then use it as a reference for the third one. Just place your finger on the 4th fret of the second string to get the F# note. You will use this note to tune the 3rd string, make it sound exactly the same:
After this is done, you will have only to tune the 4th and last string. In the Venezuelan cuatro, this string has a particularity: it is tuned one octave lower. So for getting to this sound, you will use your FIRST string as a reference. You will place your finger on the 2nd fret of the first string and this is going to be the B note, the one you’ll use for tuning the last string.