Don't use GMail. Google mines all of your communications - for advertising and other commercial activities of its partners; and also makes those communications accessible and searchable by some branches of the US federal government, and perhaps other parties.

There are less-privacy-invading alternatives - both paid and gratis - which you should consider. I'd particularly suggest trying options that are not based in the US, the UK or Canada.

(The harder part is avoiding conversing with people who use GMail, but the more of us leave it, the more that can be realized.)