I went through exactly the same thing, i made a mini bankroll from SNG's then started playing ring and made approximately no money from the cards for about 5 months. However in that time i cleared about $1500 of bonuses so my bankroll grew quite nicely and when i improved my game i was at 50NL and soon at 100Nl. Basically its all about the bonuses, they'll give you a safety blanket while you're working out your game. If you want to clear bonuses at a reasonable rate you'll want to play ring games over SNG's, and once you learn ring i believe you can make more money from the same bankroll than you can at SNG's.