From nearly 25 years defending the accused in state and federal courts, here's what makes a lawyer a good plea negotiator:
1. Prepare the case for trial. Nothing convinces a prosecutor like knowing the defense is ready, willing and able to go to trial (and appeals) and possibly prevail.
2. Try/appeal cases. Trying cases keeps lawyers sharp. It confirms to prosecutors you can and will try cases. Appealing if and when you lose does the same (and often results in favorable decisions).
3. Charge hourly. A lawyer should get paid for the work she does on a case. Charging on an hourly basis is usually fairest, and helps spread any financial burden over time. Saavy prosecutors suspect that defendants may be reluctant or unable to come up with a larger so-called trial fee under typical "flat fee" arrangements.
4. Put it in writing. Memorialize discussions with prosecutors via email or letters to them (copy to client). If it ain't in writing; it ain't.
5. Criminal defense is a stud poker game; play accordingly. "Winning" is less about the cards you're dealt (which cannot be changed) than in when you play them, how, with whom, and what is at stake.
6. Carefully consider every communication. Everything that is said or written, when and how, affects the outcome.
7. Keep the client well informed. It is their case, and their future. They deserve to know what is going on. Their perspective and input are invaluable.
By far most criminal cases are plea bargained. The lawyer who gets a good plea for his client - quietly, efficiently, effectively - is a winner.