By way of background, I was never a PD but I worked at a PD's office for 4 years throughout high school as a gopher / investigative intern / furniture builder / etc. I know a lot people who are PD's-for-life, and others who wanted to be. My dad was actually the chief assistant PD for a number of years, and then the acting PD between a resignation and appointment of the new guy, so I know a lot about the office.
First, the extremely low salaries push people out - even those who love it and don't want to go. It's tough to live on $35,000 - $40,000 per year. That's just a fact. You went to the trouble of going to law school, why do you want to earn less than a high-school teacher, a garbage man, etc.? Salaries go up if you can stick around long enough - a chief assistant in a decent sized area can make $80k-$100k, but you need to endure many years of poverty to get there.
Also, you need a few things to be a successful PD: First, you need to have a thick skin. The majority of your clients suck. They don't realize that getting a free lawyer is a privilege not often afforded to people around the world. They lie to you. They blame you for their failings. They accuse you of being in cahoots with the State. This can get to people.
Second, you need to love to try cases, because you will do it all the time. Plan on at least 2 trials per week when it's busy in addition to daily court appearances, etc.
Third, and this might be a subset of the first point, accept that people make irrational decisions. It might not be a good idea to go to trial, but your client wants to out of principle. Fine, give em hell - you aren't going to jail if you lose, the client who made the bad choice is. Even if you think a client is making a bad decision, you need to be able to put that aside and work as if they are making a great choice. Often, I saw PD's get frustrated and kind of "mail it in"
Fourth, fear no judge. Judges come in all shapes, sizes, and personality types and can be great, neutral, or total pains in the ass - or sometimes all three in the same day. You MUST always be polite, you must be careful not to push it too far, but keep your client from getting screwed. Keep in mind that if you set every case you have for trial, you can paralyze the division. The judge knows this too. Start to really push cases, put the screws to the state, file lots of motions, and schedule lots of hearings, and the judge will get in line, especially if you do a good job.
Finally, if you get the chance try to intern with the FEDERAL pd's office. The pay is much better (in the $70k range) and you deal with a lot less cases. However, these offices are almost impossible to break into. If you get in on the ground floor and people know your name, you have a much better chance of landing a job there. The trade off is that all of your clients will face draconian penalties, ridiculous evidence rules, and sometimes extra-shifty AUSA's who will fuck you if they can, even if it's unethical (this is a minority, but it happens)
If you want to know what it's like in a big firm environment, I found Double Billing to be pretty accurate, if occasionally histrionic.
Defending the Damned is a good book about PD's, though it's an extreme example and probably quite different from anything you'll experience. The overall tone about the camaraderie of the defense bar and PD's in particular, is very accurate and universal IMO
Roy Black can come off like a pompous ass, but Black's Law is pretty interesting, about high-end criminal defense and how bad the gov't (in this case, represented Janet Reno) can screw you if it wants to.
One last tip: To be a Trial Lawyer by Lee Bailey is a good general guide to how to actually prepare and try a case. A friend of mine read it before his first case and won!
