Watch the Octaves: 2 online guitar lesson by Robbie Calvo from SoloCraft
A huge part of attaining clarity from your octave lines is the right hand technique. Many guitarists favor using the edge of their thumb for a warm full tone. You can see from the video that I approach the right hand technique differently as I play with more of a strumming type attack with the nails on my thumb and fingers. You could try using a pick as well. This is where experimentation comes in to find your own voice. Left hand muting is very important too. You are spanning three strings to finger an octave shape which means you have to mute the string in between those notes. You also need to mute the notes either side of the octave shape. Study the performance and see how I handle this and then apply that to your performance.