When joining any network like Steemit, I suppose your first objective, the very reason you came here is communicating with other people you meet here. So, unless you're a schizophrenic, you would be engaging in conversations with other people. And when you come to a new place, filled with people you don't yet know, who are in lively conversations with each other, the best strategy to mingle is to latch on to the ongoing conversations, not to start your own and hope you yell loud enough to detach a lot of people from their ongoing talks...
Commenting first and starting your own threads later came naturally to me, and I hope to most. I guess the minority that comes here with the sole objective of making a quick buck don't really care about the true purpose of this beautiful decentralized blockchain app.
Still, commenting in a respectful and meaningful manner seems to be somewhat of an acquired skill and also not every occasion lends itself for such comments. If you're late to a conversation and everything has already been said in previous comments, how valuable is it to just repeat what's said before? In these cases a short confirmation of your love for the post and / or author can be welcome and appreciated; as long as you show that you actually read the post.
When you finally feel comfortable enough to start your own conversation, the importance of commenting shoots up exponentially; if you want your brand new followers to stick with you, you'd better make sure you do not ignore them when they give their opinions, good or bad. This is in my opinion even more important than upvoting or resteeming.
Helpie has been great for me and a lot of others in this respect. I've learned so much from this community and was so lucky to be accepted in their circle. Finding a community to be part of is another reason why commenting is so important; it is infinitely more easy to join a group of like-minded people than to start your own group from scratch! Mingle, ask someone to dance, occasionally offer to get the drinks... mingle!
Thanks so much for this valuable post, @oghie and @helpie!
edit:
Just for fun, here's my current numbers on posts and comments:
In case the image doesn't show: 66 posts and 397 comments...
Thanks for the contribution.