Struggling at work - looking for tips.

What I do to ensure not leaving bolts loose is this. I have a tool cart, just like 99% of all mechanics do. By the end of the job all of your tools are in your cart right? I put all of my tools away in my tool box at the end of every job. While doing this it helps remind me to double check my work. Just holding that wrench in my hand again, or that ratchet with the 13mm socket stuck on it. It also keeps my cart clean and ready for the next job, and I feel way more organized. It might slow you down a little bit, but it is well worth it. JMO