Some art posting tips for the artists migrating over here, as a Certified Tumblr Artist Veteran™️ who's never stopped posting here in a decade:
1. Don't add links under all of your posts
It means they won't show up in search results or tags, it's better to have the one pinned post with links at the top of your blog or links in your description. Alternatively like I do, you can keep links out of posts when you're just posting your art on its own, then only add them to posts that are specifically calling to visit another site (e.g. you're promoting a Kickstarter)
2. You don't need to use really specific tags like on Instagram, and the first 20 ones you use are the ones that count
I remember a few years back it was passed around that the key to getting attention on Instagram was using alternating niche tags, but now some artists just do it everywhere when it won't really do you any favours here.
The first 20 tags you use are the ones that appear in search results, the best general tags to use are #art and #artists on tumblr then after that use ones more specific to you such as say, #illustration or #digital art (also notice these have spaces between the words as tags mostly do on this website)
3. Keep your posts pretty and clean looking
A lot of users can be particular about what they have on their blog because they're trying to keep it clean and aesthetic looking, if your posts are overall pleasing to the eye including the description I've found people are more likely to reblog your posts. That means avoiding massive paragraphs with needless hashtags in the description, and uploading high-quality photosets of your work that shows off the pretty details of your artworks!
As a general rule if you have a bunch of sketches or similar images they'll do much better as a photo set than posting them all individually, unlike on other social media posts do better with quality over quantity, and your post won't "expire" after like 24 hours - people will keep reblogging a post for years here especially artworks.
One downside for a new artist posting here is there's no algorithm to show you to random strangers to get a momentum going, and it can be hard starting off from nothing because of this. However, if you search around you'll find that there are quite a few art curation blogs here who will be happy to either reblog your art or take submissions and post your art on your behalf with links back to your blog. Just be sure it's a blog that's actively looking for artists and not a random user that you're pestering to promote your work, they usually indicate in their description that they're accepting submissions.
You may even find yourself drawing the attention of the Tumblr staff who run multiple art promotion blogs and often feature artists on the Tumblr Radar (it's a little spotlight section visible both on mobile and desktop that features your post to the whole userbase, and it's very exciting getting an email that you've been selected! :D)
5. Read the tags under your posts
Due to an old habit that the website collectively held onto from the days where replies hadn't been added to posts yet, a lot of people use the tags to basically ramble their thoughts under a post they're reblogging.
What does this have to do with artists? Well a lot of people will think out loud in the tags about your art and you can read them all under your post, I find it really supportive and endearing and it's one of my favourite things about posting here!
6. Customise your blog on desktop
Something that new users who only use Tumblr on mobile might not notice is that your blog actually has its own webpage on desktop outside of the app with the URL "yourusernamehere(dot)tumblr(dot)com"
You can actually customise this page in HTML and there's a lot of premade layouts called "themes" either available for free or buyable in marketplaces - this can be a pretty accessible and cheap alternative to a custom portfolio website if you don't have one!
I hope some of this is useful, good luck with getting your art in front of new eyes! 💫
