Hi there,
Congratulations for your hard work!
Nowadays, AppStore is flooded with apps and games (as you say), some of them, really bad and not polished (Apple seems that don't care about quality of apps and games lately).
You need to do, some hardwork again, to give your application some extra exposure; that is what i do.
1. There is a lot of websites about iphone games / apps, you need to talk with webmaster to try to get some review for your app; most of them never will answer to your e-mail; some will do for a few $; others will do for free. Anyway, you always can go to forums of this websites and talk about your game. (If they accept to do a review, you will have to send some promo codes).
2. This may seems a bit tricky but... Give some promocodes on big forums (like toucharcade), exchange it for reviews on itunes (give about 10 or 15 promocodes and you will get 25% reviews, that, will definitly improve your sales).
3. Do a website for your game and a video too, its important that people can see app before buying (i mean see somebody playing, not only static images).
4. If you are enough lucky, Apple, misteriously, will promote your app on some category (Noid was on New & Notheworthy category). It's really a mistery, how Apple select this app, but definitly, improve your sales.
5. Do a lite version, sometime after app release (about a month). That will give you visibility of your app again. This lite version must have a clear button (BUY), which link you with to the paid version of application. Normally the conversion rate is about 2% to 5%, which means each 100 people who download your lite application, about 2 to 5 will buy the paid version.
6. Create twitter, myspace, facebook, etc to promote your application, some people will follow you, and some companies too, so you can get in touch with them. (twitter preferred).
7. Google Adword, Banner, ads... Normally dont work very well, i mean your cost will probably be superior to sales.
8. Its obvious but... Do more applications!, if you can have some applications selling at the same time, you improve your benefits.
9. Try to avoid 0.99$ 'technique', cause you never could drop this price and people loves 'on sales', on some interesting dates (like christmas), which improve your sales.
10. Have luck, its, of course, an important factor too.
This above methods and some luck, give you a decent of downloads daily for sure.
I think hard work is about 80% and luck is about 20%.
Now, i am almost finish my second game which will be available first week of december.
I wish you work and luck!
King Regards, fjsantos.