With time I learned that (or got more practice) it is unlikely I actually forgot something. Probably I just don't remember packing it. 95% of the time when I fear I didn't pack some silly thing, there it is, in my suitcase,when I arrive. Thank you past Swizec!
A big part of it is also that I always pack my suitcase in the same way and I always put certain things in certain spots. If I am closing the suitcase and the thing is not in its spot, then I stop and put it there.
Especially important for passports and other such documents. Always put it in the same place. If it's not in that place, then it isn't packed.
This reduces the amount of checksuming you have to do.
Oh and all you really need is your passport and your credit card. The rest is replaceable.
For some of us, depending on the destination, prescription sunglasses also fall into the category of essentials. Learned that lesson the hard way.
After years of doing this and feeling silly each time I started checking the oven before I left the house and told myself outloud, "Yes, the oven and stovetop is off". I was surprised how effective this was.
Interesting to read this article today and other's solutions to the same problem.