Here’s the thing: You don’t. You can’t. There are no magic words to make someone see things your way. You can give them ideas to mull over, but you can’t convince someone who doesn’t want to be convinced. You can be open, express your views and give your reasons to anyone willing to listen, but that is the extent of what you can do. Some people may eventually come to you for advice; welcome them and guide them as you can. Most people may take some bits from you but never start actually caring. That’s ok, that’s their way.

You can’t force people to do things your way, nor should you try. Just be honest.

If you want to learn Linux, install Gentoo. That’ll give you a pretty good understanding of what’s going on. It’ll be an intense process though.

If you just want to install and use Linux, pick one of the usual suspects: Mint, Fedora, openSUSE Leap/Slowroll, whatever. If you come from Windows, picking KDE Plasma as your desktop environment (DE) is a good choice. Mint’s Cinnamon should be good too. Picking a popular distro usually means troubleshooting is easier, since someone else out there most likely has the same issue you have, and documentation is more comprehensive.

Remember that many distros provide a live environment you can run from a USB stick. Try a couple with different DEs and see what fits your needs. Honestly, the distro doesn’t matter that much, they all do the same thing, more or less. Maybe try to pick your DE first and then just go from there.

If you want a simple answer, pick Mint.

Posteo is affordable and, at least to my liking, private enough.