I did a bunch of independent traveling back in 2005 and couchsurfed in a number of cities in Europe and Asia. Since then, I've hosted several surfers at home in the US and surfed sporadically on road trips. I've also used the site to meet up with locals for drinks/coffee when I had other accommodation already lined up.
IMHO, couchsurfing works best when the focus is on cultural exchange and meeting new people, with free lodging being a pleasant secondary benefit. When someone is in it purely for a free place to crash, it becomes obvious to the host and can be a major turn-off. I'm definitely not implying that's your mindset...it's just something to be aware of.
My best bit of advice would be to get involved with your local CS community and meet other couchsurfers in your area before you leave on your trip. Pretty much any city of 75,000 people or more will have a designated group on the website that you can join. I've been involved in the CS groups for Seattle and Minneapolis and it's pretty common for someone to be organizing happy hours, potlucks, or other meet-ups more or less every week. By getting to know people locally, you can build up your reputation (vouches and references) on the web site, which makes you more of a "known quantity" to hosts. Most hosts will tell you about getting requests from people who throw together a half-baked profile with no references...these requests often get ignored. In very popular cities (London, Paris, etc.), hosts get bombarded with so many requests (sometimes 50+ per day) that they have to deny most of them.
Which leads me to another suggestion: because there's so much competition for hosts in popular cities, you might find that you have the best luck in cities that are big enough to have a good-sized population of CS hosts, but aren't so huge/popular that they're getting inundated with requests. Think Missoula vs NYC.
Some of the best experiences I've had in my travels have involved couchsurfing...if you go into it with the right mindset and a little prep, I'm sure you'll have a great time, too!