2 things:
1. Make sure you reload back to the max buyin when your stack drops 5% below the max buyin. This will ensure that when you do double up, you get as much as you can.
2. Try playing more tables at once. You get to play more hands without sacrificing quality of hands. I started with 2. It seems a little crazy at first but a month later I was 4-tabling without any problems.