I'm about to graduate from law school, and this is a potential option for me as well. So I took a solo practice course some alumni were offering at our school. They have extremely successful practices, so I thought I'd pass along some of their advice.
One thing that gets repeated over and over is to create systems for doing your work. Break things down into component parts and create a process for fulfilling it. For example, if you do get a receptionist or secretary, what do you want them to tell clients walking in the door? Also, how are you going to allocate the resources you do have to maximize the time you can spend providing a service to the client. It sounds like micromanagement, but it's really a matter of delegation and how to get it done. Someone said it earlier, but think like a businessman, not a lawyer.
Also, don't just see your salary as a function of whatever is left in the account after paying overhead. Think about what you'd like to make, within reason, and make it part of overhead. This isn't a guaranteed paycheck, but it will help you to understand exactly how much work you really need to bring in to get your practice where you want it.
There is a lot of great advice on here, especially from those already slugging it out. So, if what I've said conflicts with them, chances are good they are right(er) than I am.
Another book I could recommend is The E-myth Attorney. Very short and to the point. I've also heard great things about the Jay Foonberg book.