Writing the Intro

You could start with a suspended or mystic chord, then quickly resolve it as seen in this video:
You could start by repeating a very fast sequence of notes, increasing in volume. After about 4 bars of repetition, you could "layer on" some other elements like the melody or bass, so as to give the feeling that more than one musician is performing. For example:
You could start by establishing a groove, as in playing percussion for the first 4 bars or so.