I'm trying to live offline first. What does this mean? I assume that I won't have an internet connection and adjust when I do, rather than assume that I will and break down when I don't. Here are what I'm changing:
I favour asynchronous communication. This pretty much means email. I prefer to talk to people on the phone or face to face if I want to have a conversation. I do make use of communication systems that emulate conversation (SMS, IRC, XMPP, and Pleroma) sometimes, but I find that the less rushed atmosphere of email results in more being said, and better. The "slow" nature of email also sets it up well to being downloaded and accessed offline, which makes it easier to stay up to date with limited internet access. I achieve this using mbsync, notmuch, and Emacs - a fairly standard setup.
I keep media offline. Not just media, most things. I have extensive caching enabled - I forget things a lot so end up searching for the same things over and over. I download and watch videos offline, and have all my music offline. I also have copies of books and dictionaries offline, so I don't have to go online just to search words. There are benefits to this beyond simply accessing your stuff anyway, like actually owning your media.
I use tradition programs over webapps. I don't have a problem with people choosing to locally self-host; this is pretty common for some things like Tiny Tiny RSS which is a great piece of software. This avoids the fundamental problem which is needing an internet connection to do a simple task. Offline programs also don't have the same distribution cost as web apps if you're not self hosting (as in, they don't need servers), so you're less likely to be paying with your data.
I learn to RTFM. I condemn the concept of telling beginners to RTFM rather than actually helping them when they ask for help, but these things start somewhere and manpages are pretty helpful. I have printed copies of a lot of manpages (nothing special, I printed them myself) and documentation for whatever libraries I'm using, and also reference books for programming languages. Being able to flip through and find what I want is really beneficial, and I think it has improved my abilities as a programmer.
Four simple things. They have changed me.