These simple things will improve your experience on the web.
These are things I always install and notice immediately if they aren't.
They don't require any behaviour change and work seamlessly in the background.
Block ads in your browser.
Ublock Origin is available as a
desktop chrome browser extension
or
Remove recommendations on youtube (great for kids)
Unhook is available as a
desktop chrome browser extension
or
Undistracted is available as a
desktop chrome browser extension
These are nice to have but may require minor changes in the way you use the internet.
Firefox on mobile allows installing extensions to block ads etc, which chrome can't do.
Firefox is available for android or iOS
Watch youtube on mobile devices without ads or distractions.
Firefox browser on mobile with addons is a simpler alternative.
Install newpipe
Downloaded videos don't have ads, but it means you can't just click the link in your browser to watch them, you have to leave the browser to download the video and watch the downloaded file.
This tool can download any video, but not all videos are legal to download due to copyright, so please be aware of the rules in your country and the particular site or video you're using.
This tool works with many sites other than youtube, and is often simpler than creating yet-another-account on a random video website to watch tv.
Install yt-dlp for the command line. Stacher looks like a good GUI for it but I haven't used it.
These are projects I find technically very interesting but don't use because they aren't easy enough for non-technical users to interact with.
Pi-hole blocks ads and trackers before they get to your computer by acting as a middle-man between your router and your computer.
The nice thing is it can block ads for every device on your network without needing to install anything on those devices.
The hard thing is it can make websites not work properly and making them work is not usually easy for most people to work out.
Installation instructions for pi-hole
Easily send files directly from one computer to another.
This avoids the need to upload to a server like dropbox or google drive.
But it requires you to keep the application open while the recipient downloads the file, which may not always be immediate.
Install Magic Wormhole for the command line, or Rymdport for a graphical interface.