Welcome to Hubski! It's a great place, indeed.
Either commenting or posting is welcome, as they both could promote thoughtful discussion. I saw people welcome you here already, and I don't know how much they've told you, so I'm going to reiterate what I think is important to know here:
Your name matters. Here, people are able to build genuine connection with each other due to the way conversations are ran. People will remember what you said, and you have time to think before posting. You seem like a reasonable person, but I'm going to say it anyway: take that time. The reason being...
People are genuine here. Often enough, it leads to serious clashes even between friends. Sometimes, people will say things that will incite anger in you. Take the time to sit back or take a walk and think about what you want to say, and whether you want to say anything at all right now. If this is something you're not used to - which, coming from Reddit, you might not yet be expecting of yourself - it will take some effort. I'm sure you'll be fine in this regard, but, again, worth saying.
If you need a place to start, there are a few tags you might want to participate in, commenting, posting or simply following.
#AskHubski and #TellHubski are self-explanatory, and your topic doesn't need to be special to apply. If you notice a bug in how Hubski works, feel free to post the description to #bugski; the search is currently broken, with the devs working tirelessly to fix it. Site-wide announcements are made with #hubski and #devski, so you might want to follow those.
I'm a Russian native, and this being a US-centric forum, people seemed to be interested in knowing what it's like to live in the mystical red land, so I post under #russiabynatives sometimes. If you're interested in the US politics and the shitstorm that's going on there, be sure to follow #sillyseason (about the silly part of it) and #seriousseason (about things not so funny). I'm sure you'll find a bunch of other tags to follow; just check the Tags tab.
You might also find it interesting to follow the Hubski IRC channel, which you can access with the link below. There are quite a few dwellers, including myself, and people who visit sometimes (usually with prior announcements).
Welcome to Hubski, and best wishes to your stay.