Newcomers to Dreamwidth

1.) Markdown Posting

If you miss being able to post via Markdown instead of HTML, the beta features page has an option to opt into the "New Create Entries Page." This allows for creating posts using Markdown, much as the comment function has a Markdown option. Just as with cohost, HTML input into the post will overrule/overwrite the Markdown you're using (if you want to get silly with it).

2.) HTML and CSS Stuff

If you instead want to jump feet-first into the brave new world of all-HTML posts, I recommend w3schools as a reference and primer. They have really good walkthroughs of current-gen HTML5, as well as CSS (and even JavaScript, though that doesn't apply here). I refer to them regularly when Markdown is insufficient and I can't remember what the various style options for an HTML element are.

3.) Your "Dashboard" is Public

I haven't seen any evidence of this being misused here, but it's an old carryover from the LiveJournal days and people coming from cohost tend to be surprised by it. Everyone can see what shows up on your Reading page, unless the original creator of the post has restricted that entry. Not only is it an open HTML link, but it's literally a link on your main page for anybody to click on. If you wouldn't want someone else seeing that you're following something, you might want to use a separate feed-reader and just subscribe to the feed there (which you can also do for actual public dreamwidth journals, as they have an RSS and Atom link on each front page).

4.) You Can Customize Your Journal

Another carryover from the LiveJournal days, but also something which used to be a big deal on Tumblr and wasn't possible on cohost. If you're into the CSS crimes stuff, or just want something which reflects your personality/interests, you can customize your journal's CSS to give it a unique look. You could easily get very in-depth with this if you wanted. Or heck, just make it look (mostly) like cohost did if you'd like - you could pull the CSS off cohost itself as long as it's up, or use their rehosting tool (once it's live). I actually specifically incorporated the "cohost font" of Atkinson Hyperlegible onto my page because I like how easy it is on the eyes.

5.) Tags Don't Work Like Cohost

Yes, you can tag your posts - but unlike cohost and Tumblr, they aren't global. You can't click on a tag and see other people who have used it, unless it's a tag in a community (and even then, those community tags only apply to that particular community). There's no "I enjoy seeing the art people make, so I follow the 'artists on dreamwidth' tag." Interests are the closest equivalent; instead of each post being tagged individually, people list their overall interests and you can either search them or browse through them to find people who've said they like that thing. That said, there's nothing requiring people to post about the things they're interested in.

6.) It Takes a Bit More Work to Connect

This is a very early "web 2.0" system. As in, "web 2.0" was coined in 1999 per the Wikipedia article I just linked and the code for LiveJournal (on which dreamwidth is based) started being written that same year. There's been 25 years of intervening development since then designed to make the "social" part of social media more seamless, and this place doesn't really have any of that. That means you have to do more of the legwork yourself. You can't engage with posts or users without actually engaging with them - there's no reblogging/rechosting, no "likes," nothing on any post except perhaps a comment box. So you're going to have to search, reach out, or maybe just DIY it. There are communities such as this one and addme which make it possible to find other people, and ysabetwordsmith's followfriday is a community meant for recommending other communities. You can also create your own! It looks like someone's already made eggbug_writes as a community for former cohost writers and writing-prompt-makers, and there's nothing that says you can't create some other central meeting-place communities for people to regather and find one-another again.

7.) Protect Yourself

You can turn off or limit Private Messages in your Account Settings under the Privacy tab, which is also how you can turn off anonymous comments and IP logging (which is on by default). You can also ban users directly from commenting on your own journal page there too. I encourage you to liberally take the actions you need to make it hard for other people to make your life more unpleasant. If anybody is actively violating the Terms of Service (section XI - Member Conduct), you can also report them... but there is no sitewide blocking or muting like there was on cohost, so keep that in mind and take proactive steps to make sure you aren't giving access you don't want to people you don't want having access to you. This place is generally more insular due to its old design functions - it takes work to search out others, which limits discoverability of people you want to know and people you don't in equal measure - but it's still possible for you to show up in the Latest Things global feed (which is a true global feed), so please take steps to take care of yourself in advance if someone barging in and being an awful human on your page will be worse than a "sigh, delete, ban" response for you.

I haven't seen anything of the sort happen, but that doesn't mean it can't. I never saw any of the cohost-related issues first-hand either.