Getting distribution is tough, and I'm still learning this game myself. AND, on top of that, it's all changing so rapidly that much of what I learned from my first film will likely be different when I get into the process for my new feature...
Nevertheless, here are some useful tips that I think will still be important, regardless of the changes to the distribution world:
Be prepared -- You don't know when (or from where) an opportunity will arise, so go ahead and make up your marketing materials now. Posters, postcards, an electronic press kit, stills, trailer, etc. One of the compliments I received -- and one that I was quite proud of -- was that I was among the most prepared of any filmmakers a distributor/aggregator had worked with. I felt like a complete neophyte, but it turned out that, by being prepared in advance, I was able to quickly take advantage of a number of opportunities.
Consider Alternate Models -- We all want traditional theatrical distribution and, after that, DVD. But online models are expanding quite a bit, and if your film is right for the web, it might end up making more of a splash there than it would have in a tiny traditional release. It may not, of course, but the potential is there. And it's worth considering.
Be Realistic -- If your film is a no-budget indie with no stars, be realistic about its chances in the marketplace. Yes, you MIGHT get into Sundance. And you might also win the lottery. I haven't done the math (I am a filmmaker, after all), but the odds are probably pretty close. And without some way to get the word out to audiences that this film should be seen (or even just creating name recognition), your film will just be another DVD on the shelf. Think ahead of time (too late in some cases, I know) about your goals for a film, and consider what you can get out of the experience if you don't get into Sundance or some other big festival. This, I admit, is the hardest part for me. Though I am realistic about my films, I still harbor those Sundance fantasies -- it's hard to keep it in check and be happy with lesser results, but getting into a lot of mid-tier fests can be a good thing (for many reasons, not the least of which is that they care about your film and often treat you like a star), and you can build momentum towards getting into other well-regarded fests, for example.
Get the Word Out -- I can't say this enough: the more people are aware of your film, the more of an audience you're likely to get. Be your own publicist. Be creative in finding an angle for getting coverage of your film in the press. Since I shoot films in Waco, where not a lot of films are made, I am able to get the local paper to cover the filming. I also leverage my university's PR arm, which ends up helping us publicize to alums in the entertainment industry. I do local radio interviews, TV interviews, whatever. I send press releases (that I write) to arts/entertainment editors at papers and websites where the film will be screening. Contact organizations that might have a connection to the content of the film. Anything you can do to get people talking about it. Creativity is really useful here. And if it sounds like a lot of work -- you're right, it is. I sometimes feel like I am always on my laptop doing this stuff. But then, I'm always on my laptop anyway, so I might as well be doing something useful rather than playing games or surfing the internet (though I do lot of those as well).
Festivals -- Some filmmakers eschew the fest circuit. I love it, because people see the film, and I don't have to wait to find some semblance of an audience. It's expensive, I admit, but it's worth it to me. And if you get into the right festival, you can connect with distributors. My DVD distribution deal came about because of a competition screening at a Los Angeles festival. The distributor had a relationship with the festival, and I benefited as a result.
Festivals aren't the only thing -- There are networks beyond the festival circuit. My latest discussions with a distributor came about because of relationships. An actress in my new film connected me with someone who happened to be a friend of a filmmaker friend. So a new deal is being struck as a result. Networking with other filmmakers -- and actually making new friends -- can make a difference. Even though it's a very competitive arena, a lot of filmmakers would love nothing more than to help their filmmaker-friends succeed along with them.
I'm sure there are other tips, but these are the ones that were specifically important to me in the process of getting my first feature out.