I just watch "Hitler Rants about the E39 BMW" on YouTube and LMAO.
1. When you plan to do a job but know to buy extra parts for all the other misc. BS plastic that might break;
2. Watch your coolant temp. (test 7) religiously;
3. Spend hours on the forums gathering information before you start a job;
4. When you plan a job with the "while I'm in there mentality";
5. Start shopping for parts that will go bad before their needed.