If you want to learn quickly how to work up a case from start to finish, review the files in your firm's file room. Select a couple of large ones, then read through each piece of paper, paying special attention to the correspondence and pleadings folders.
When I started out at a large defense firms, I followed this tip myself, reviewing both old and active files. It was great way to learn how the lawyers at the firm worked up a case and what went on behind the scenes. I learned about the typical procedural steps from investigation to trial, and I learned how the lawyers at the firm interacted with other lawyers, as well as with witnesses and experts.
Something else that helped: during my file review, whenever I found a letter that I thought would work as a template for other, similar letters, I copied them and put them in a folder. It saved me time and made me feel more confident about my own work product, since now I had a baseline to compare it to.
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