The game is about positioning and consistency in how you present yourself as an artist. Sending off beats to artists' Twitter's and all is great. It sometimes gets you noticed. But they don't hold the real power. The people who put the records together, they make a ton of those calls. And they don't listen to any fool who approaches them on the street.
If you have an actual professional product, you'll be ahead of most of the idiots hitting them up all the time.
1) Tape. Can't do shit without a proof source.
2) Web presence. Same as above, at least from the marketing aspect of it.
3) Time. Nothing will happen overnight, or the first, second or 12th time you try something. And yeah, you will often get one shot with anybody. Nobody has time for anybody who doesn't have their shit together.
Anyway, it's late and I've been working since 5am. I'm barely cogent at the moment.