I'm also on my first grow and I can tell you what I used so far. All the mixtures I'm using seem to be working great so far.

Mixture One – 1 Part Worm Castings, 1 Part Vermiculite, 1 Part Perlite, 1 Part Sphagnum Peat Moss.
Mixture Two – 1 Part Worm Castings, 1 Part Sphagnum Peat Moss, 2 Part Vermiculite, 2 Part Perlite
Mixture three – 1 Part Worm Castings, 1 Part Perlite, 2 Part Vermiculite
Mixture Four – 4 Part Worm Castings, 1 Part Perlite, 1 Part Vermiculite, 1 Part Sphagnum Peat Moss
From http://boards.cannabis.com/grow-log/...-grow-log.html

Let me know if this is what you're looking for and good luck with starting up your first grow!