* Reading from a variety of sources (HN does provide a lot of this, click on more than just the tech articles).
* People in our age group seem to have more interest in being heard than interest in listening. Don't do that. Ask questions (which is in itself a good way to hold a conversation), even about things you wouldn't think you would be interested in.
* Learn to at least listen to opinions that differ from your own. Big bonus if you can dedicate energy to contemplating those opinions.
In addition:
* Nobody wants to hear about Game of Thrones or the latest computer game that you play. Entertainment media rarely makes for good conversation unless you share the specific entertainment piece in question (mostly sport); however, you are doing little for your future conversation ability by participating in an echo chamber.
* If you screw up people will probably forget about you, not remember you as an idiot. Don't be scared to practice on strangers.
* Keep your bloody phone in your pocket and ignore it.