Getting friends to do promotional votes and comments isn't ok on HN. This is in the FAQ: https://news.ycombinator.com/newsfaq.html. We ban sites and accounts for doing this, so please don't. Also, it's usually obvious to the HN community when this is happening, and they consider it spamming.

We want users to upvote submissions that they personally find intellectually interesting, not because they or their friends have something to promote.