I've started thing 2, which is learning tips and tricks for using my device. I will probably be using more than one device for my 23 things--when I registered I said iPad, because my library has one and Dillon said we can use it for this. But today I've been looking up tips for my trusty old iPod touch (iOS 5.1.1) and I'm learning lots. I'm reading an article of tips and tricks for an iPad running iOS 4-6, and of course not everything that works on an iPod will work on a touch, but I'm going through the article and trying stuff out to see what I can do.
There's a lot, so I'm not going to get through it all in one go, but I will come back to it later and update this post with some kind of summary.
ETA: I finished the iPad article, and looked up another that was specifically about the iPod touch. The tips broke down into several categories: things I already knew, things I didn't know but only because I'd never gone in and looked at all the details in the settings, and things I would never have thought to try (like holding down a key on the onscreen keyboard to reveal other hidden keys). Overall, very helpful.