I think the future of game publishing, from a designer's point of view, is in self publishing. It's a lot harder than the 'fire and forget' system of getting an established publisher to make your game, but your chances for success are vastly, VASTLY, improved.
If you ignore those odds and want to submit a game anyway I suggest the following:
- Make sure your prototype is ready to play*. If I can't play it, I can't evaluate it properly.
- Make it look nice. Art isn't required, but clip art is easy, free and will add a lot to the presentation.
- Don't go crazy with art. Art directors will always want to redo everything anyway.
- Do go crazy with rules. Clear as crystal. Keep typos to a minimum. This isn't a resume', so a lone spelling error shouldn't disqualify you. That said, if it's too hard to read or we can't figure it out, we're not interested.
- Don't worry about marketing, pricing, or presentation. Like art directors, marketing and sales directors have there own ideas about those sorts of things.
In all honesty, it doesn't hurt to try and get feedback from companies on your games, even if you know they aren't going to publish it. The more comments from people outside your circle of friends, the better your game will be. If you can, take it to conventions and try it out there (easier said than done, I know.)
Hobby game designers have this notion that their ideas are special and that if too many people see it, the idea will be stolen. For the most part, that's rubbish. The more people that see your ideas the more valuable feedback you're likely to get. Also, everyone thinks their ideas are better than yours, so stealing ideas isn't on most people's to-do list. The best way to prove them wrong is to turn your idea into a reality. That's where the value is.