My practice is a bit diverse, with a heavy volume of relatively low revenue speeding tickets, some moderately higher revenue dwi and criminal defense cases.
The biggest revenue opportunity for someone in my type of practice is personal injury cases. This includes car accidents and a variety of other accidents. Because there is so much revenue potential, there is a lot of competition as many lawyers want to do this kind of work and get in on the revenue stream. A simple car accident case with relatively minor injuries (like a rib fracture) can generate a fee of $5000 or more. Compare that with $250-400 for a traffic ticket or $1000 for a DWI. A good case can lead to fees of $25K and up. And the best cases, which are quite rare, lead to fees in excess of $100K. If you just get one of those cases a year, you'll do pretty well.
As an injury lawyer in Albany, NY, I see competition from big TV advertisers and a variety of lawyers advertising in the Yellow Pages. Different firms have different approaches to how they handle things.
The largest TV advertiser is really four actors (they are lawyers) and a staff of retired insurance claims people. The staff process the cases and try to turn them into money. The lawyers rarely go to Court.
Some of the Yellow Pages advertisers really aren't injury lawyers. They get cases in and then refer them to a real Albany injury lawyer. The referrer gets a share of the fee, usually one third of the total fee.
There are some very good injury lawyers in the Albany, New York area. They have great experience and frequently take cases to trial. One of the best was Dick Aulisi. He's now a judge. But there are several others that do a really good job.
There are good lawyers and there are good marketers. I like to think I'm both, though I'm probably a better lawyer than I am a marketer. I haven't gotten many personal injury cases through advertising, though I do get a few through the web. It's another part of the learning process.