I agree with everyone else in learn your name brands that you like. I never bought fabric on line either until I joined this board, except once when I ran out of a fabric and had to find it on line. But in that case I knew what I was getting.
So I simply started paying attention to name brand products that I have never been disappointed with and have had extremely good luck finding bargains and ordering on line.
Brands that I like are Hoffman of California, Robert Kaufman, Kona Bay, Moda, P&B textiles, Timeless Treasures. I am sure there are others but I can't think of them right now.