I fold selvages together, then selvages to fold. I put the end with the selvages facing toward me -- the fold away. I was in a class and the teacher (who is nationally known) said this helps keep the wobbles away. The rest of the things I learned at the class were the all of the great techniques for straightening the fabric -- don't cut a yard of fabric without straightening.
That said -- if I need long strips parallel to the selvages (length wise grains), I always rip it. I don't rip wof (crossgrain) because some fabrics don't tear well crosswise.