One big mistake I made while preparing for the June LSAT, which I bombed with a saddening
159 (hope you all feel better about yourselves!

), was to write in all my practice material. Initially I used a separate pad of paper to write my answers and corrections in, but I got lazy toward the end and I began to write in my purchased tests. Now that I'm restudying for a retake in October, I repurchased much of what I already own, simply because I require material that won't sabotage my efforts. The other mistake I made was to assume I wouldn't need the material after the test. Supposing I approached the situation realistically, I probably would have handled my items with greater caution.
I also read a smart blurb about printing out the bubble sheets and using those to answer every question in the practice tests. It makes sense if you're trying to simulate real conditions, and I'll be using that approach starting this week.
How do you treat your material? Do you use a notebook, or do you render your books and tests useless by writing all over them?