As someone who follows dozens of these blogs and also tracks maybe ten tags related to the subject I think I’ve found out what works and what doesn’t!
1. Use the right tags!
You should be using #game development, #game dev, #game design and #indie games if you want people to be able to find you. You should also use #programming, #game art, #pixel art, #3d, the name of your engine or any other software, the tag for any game jam you are participating in and so on where relevant. Remember: there’s no shame in using lots of tags, you’re just making it easier for those of us who wants to find you!
2. Post Screenshots and videos
It’s very difficult to get excited about a game solely through reading about it. Post screenshots of your progress, everybody loves to see your game evolve. Videos is also an option as they can show off gameplay
3. Don’t leave it at the art
Posting art content is great. But do not be afraid to post more technical posts. After all, a big bunch of those browsing these tags are making games themselves, they understand and might even be very interested!
4. Write personally
You are not EA games, but that is a good thing! You can allow yourself to be personal. Write about your thoughts and feelings regarding the game. Write about your failures as well as your successes. Don’t fall into the PR social media pitfall! People don’t wanna read press releases, they wanna read about you making your game!
5. Be active in the community
To get love, you must give it away. This is true not only in life but also on tumblr. You can’t expect to get loads of support if you’re not supporting the community. Follow other game blogs and like everything that you find cool. Don’t reblog too much though (see next).
6. Stick to the subject.
If you want to followers, this is a no brainer. People might be interested in your game, but not so much in the 10 anime gifs you post every day. If you spam unrelated stuff, people will unfollow or not follow you at all.The best thing is of course to have a separate game dev blog
7. Don’t limit yourself to tumblr!
It is always a good idea to interact at as many places as possible. Browse the forums like indie DB and link your blog
8. Most importantly: Don’t give up
Your blog is not just for promotion! No, mostly it is for keeping yourself motivated. Your blog might not get a lot of followers and support right away. But hey, even if not everybody like or reblog or follow, people do see you. If you keep posting content and follow these guidelines, people will come. There’s nothing like seeing a project develop over the months! Keep motivated!