There is a mechanism already in place to do this
During your first two posts, a message is shown on the post composer pane:
Welcome to Arduino Forum — thanks for starting a new conversation!
- Does the title sound interesting if you read it out loud? Is it a good summary?
- Who would be interested in this? Why does it matter? What kind of responses do you want?
- Include commonly used words in your topic so others can find it. To group your topic with related topics, select a category (or tag).
For more, see our community guidelines. This panel will only appear for your first 2 posts.
This text, and that of the “community guidelines” are currently just the stock text provided by Discourse, but it is possible to customize them.
There is also a “Greetings!” PM a new user is directed to read after signing up. This contains an interactive tutorial with a bot where they learn about using the forum and demonstrate their understanding of that information: