Watch the Avalon online guitar lesson by Brooks Robertson from Essentials: Boom-Chick Fingerstyle Etudes
As you start learning this arrangement of "Avalon", notice that the bass, chords, and melody are all played simultaneously. The most efficient way of doing this with the fretting hand is to play a chord form (also known as a shape or grip) that allows you to play the root of the chord in the bass, some kind of harmony (chord tones) on the middle strings, and the melody on the treble strings. This is a technique which is used in every song we'll cover in this course, and it's commonly used to arrange all sorts of songs for fingerstyle guitar. So, be sure as you work through the arrangement that you've got the correct fingerings to guarantee you're playing the song in the easiest, most efficient way possible, which will also contribute to an overall smoothness in your playing.
Once again, the bass strings should be muffled, while letting the treble strings (where the melody is played) sustain clearly. Try to take sections of 2 - 4 measures at a time and only work that section until you have it down and memorized, then move on to the next measure(s), and so on. Finally, don't forget to reference the tabs, the notation, and be aware that there are numerous variations possible in terms of alternate phrasing, syncopation, anticipations, etc.