Not yet mentioned are the skills necessary for navigation. Just having a map and compass (part of the "Ten" Essentials) isn't much help if you don't know how to use them!

I mentioned it in a separate post, but it's appropriate here--I found a good article in, of all places, the Washington Post: Why it's a real mistake to count on a cell phone when you go hiking

It is surprising how many people don't seem to be able to follow a map, as I found out at my daughter's wedding (held out in the country) 15 years ago!

If you don't have excellent navigation skills (without relying on an electronic gadget with batteries that can fail), I strongly caution against solo hiking. Of course if the other members of your group don't have those skills either, the only "advantage" is that you'll have company when you get lost! There are classes available, or you could have a lot of fun by getting involved with a local orienteering club.