It's so great to see you working more on it. I mean, even in it's current state I love it already, but I also think there's a lot more potential for it.

Streak templates like "Drawing Basics" would be very useful for many people. Curated this could be a major tool, but I also guess that it needs a certain level of proficiency and time commitment, and people having both of those are probably more interested in having people come to their own portals.

Maybe a random theme generator would be a neat helper for the Art people, where a combination of words like "figure - forest - cyan" should be enough for a starting point if someone is looking for ideas.
Getting a daily theme mailed could be very good for keeping people in the first days.

Regarding other streaks: I normally just visit the Daily Art page, look through the newest entries, look once at the notifications, post my image, leave. So the place to reach me and hint at other Streaks would probably be the notifications. Not spamming them, but every now and then mentioning some other Streak or feature of the site. Or having that info in the sidebar or header of every streak site.