checklists are useful and all, but when you are doing something out of the ordinary, a lockout/tagout works well. This has saved me many times from many expensive
mistakes.
A lockout/tagout is a tag/lock placed on the ignition/on switch, or other thing that turns on something that will break the
equipment or mame/kill someone who is working on the
equipment. The tag includes what is being done and who is doing the work, etc. Modify for your enjoyment. The best feature of this system is that someone else also knows not to use the equipment.
Another thing that I have found unbelievable useful (and seems so obvious I don't know why I didn't think of it), is to put any and all nuts, bolts ,
hardware in bags (zip lock bags work great), and wire tie, zip tie them near the work (don't use tape, it comes off to easy), and label the bag.
And one more thing I like to do, as I leave tools in hard to find places all the time, is use a small tool bag to bring to the area of work, and count in/out the tools when I start/finish the work. Now I don't loose my tools! or better yet leave them were they can break something!
I have learned these methods while working on aircraft and dangerous industrial equipment, as they were required operating standards, and they work great.