The free stroke is different to the rest stroke in that after striking a string the right hand finger does not rest on the next string but instead moves freely over that string. The free stroke produces a different sound to the rest stroke and is particularly used when each string needs to sustain rather than be dampened.
Try using the free stroke on the following exercise. Brace your right hand thumb on a bass string to help keep your right hand steady.
The cross above a note with a dotted line indicates that you should hold that note until the end of the dotted line.
The next exercise combines free strokes on the first two strings with a simple bass line. Special attention should be given to the use of the right hand thumb on the third string (bars 2 and 3).
To get the correct effect for this exercise hold each bass note until the next bass note (2 beats).
The next exercise is a simple Spanish guitar piece that features an open first string played repeatedly after every bass note. This is another example where the free stroke must be used. You will also notice that the thumb is used on the second string.