Watch the Am Blues: Chord Tones online guitar lesson by Rob Garland from Melodic Soloing: Blues Chord Tones
A minor blues often contains variations such as a V chord that is a dominant 7th, (not minor) and an approach chord to the V7 based off the vi degree such as this example in, the key of Am:
|Am7 |Am7 |Am7 |Am7|
|Dm7 |Dm7 |Am7 |Am7|
|Fmaj7 |E7 |Am7 |Am7||
Try playing the chords first and play along with me. We can still address the chord tones such as the 3rd of the chords, only now they are b3rds. For the Fmaj7 chord, we could play an arpeggio and grab the 3rd of the E7 chord, the note G#.