One indispensable self-training technique is to go to court and observe the proceedings. Mentally translate to yourself. Write down the terms that stump you, then look for solutions in dictionaries. That depends on which court, and on your perspective. When interpreters are hired by private parties, the rate of remuneration is negotiable.
Interpreters cover virtually every kind of case in the municipal, state and federal courts.
Some types of proceedings are formulaic and predictable, and can be dull. Sometimes the work is thoroughly fascinating, exciting, dramatic, challenging, stimulating, and fun. But if you ask around, you will undoubtedly find that most interpreters will tell you they enjoy their work.