I’ve used a variety of approaches over the years, from manual to semi-automatic. Here’s some different things I’ve done:

Initially I would publish a note, then use the interactive Bridgy Publish form from my account page. Your account page is https://brid.gy/twitter/isellsoap. Paste the URL of your note there, choose the options whether you want your original link appended to the tweet, then preview it. If it looks good, publish it. I then would copy the tweet’s URL and add it on my original note as a syndication link. See below on this note for an example of that syndication link.

After I did that for a while and it was working smoothly, I started to automate it more. Bridgy Publish lets you send a webmention to trigger the publish. I set up a custom bit of PHP code that would let me click a button to send off that webmention for the note I wanted to publish. Sending a webmention is a pretty simple POST request, so I used the WireHTTP class for that. When publishing to Twitter, the successful Bridgy response includes the Twitter API data for the tweet. I wrote some more code that processes that response to get the tweet’s URL and updates the syndication link on the note.

Note that all of this is separate from the Webmention plugin itself. The code for my semi-automatic publishing isn’t part of a plugin and isn’t very polished code, so I haven’t released any of it. If I can find a way to make it more user-friendly, I might release it, or at least write a tutorial with more guidance.

https://php.microformats.io is a useful tool to debug the microformats in your posts, by the way. Here’s the parsed result of this very note. The in-reply-to property is what Bridgy Publish uses to post a reply tweet. The syndication property is one way Bridgy maps your original post to the Twitter copy for sending responses back to you — particularly if you don’t include your original post link in the tweet.