Thomas- the 700 series will happen when you least expect it. My freshman year of college I struggled in my Sunday night home league and shot 450. The following week my bowling coach had his son hold a 2 hour clinic for the bowling team and I worked on a few things as far as my hand release and ball speed. That following Sunday I threw my first 700 series- a 706- and I think I threw another 10 series over 700 in that league alone. Once it happens, the floodgates should open, but others are right in saying that you need to just bowl naturally, not for honor scores, and take the series one frame at a time.
Matt