Best advice I can give (and the thing you will hear most often) is don't think about it. Don't add up your scores, don't get ahead of yourself. If it's going to happen, it will. Same goes for 900 or 1000, 300 games, etc. I shot 787 just by relaxing, going out there, and concentrating on hitting my mark (yes, see, crankers and two handed bowlers can do that for more than 3 shots!). Obviously I had something going there because the very next week I shot 298.
Advice Cara gave me 3 years ago - "Focus on only one frame at a time. It's not easy and takes practice, but once you master it, I promise you'll see the results". Well, I have. Hope it works for you too.
Cheers.
Tim.