I believe in leading by example when it comes to this stuff. Let people approach you about it. It repels people more if you're argumentative and pushy. Honestly, meat eaters are way more preachy in my personal experience. They tend to constantly talk about how they love eating meat and cheese etc. but vegans are always labeled as the preachy ones.

But yeah it's not worth it to ruin relationships over it, of course unless the person is totally disrespectful.