To promote Steemit post, I use relevant tags and community tag. It will help you to reach your content to the right audience. I try to engage with people in the comment section. It is a good way to get to know each other. Hope they will come and check out your blog.
I have not promoted my Steemit posts outside of Steemit that much. I shared my posts on Facebook few times. There are many contests on Steemit. Sometimes I participate in the contest. It will give you a little more exposure. The most important thing is, whether you win or not, you always learn something from contests.
At the beginning of my Steemit journey, I did not spend much time on Discord channel. Now I think I should have spent more time over there. Anyway, I'm active on Discord now. I share post link in the post promotion channel. Sometimes I participate and chat in general chat channel. Discord is really great to meet people all over the world. You can share what you know and learn from others.
Discord is indeed a valuable tool. Not only for promotion, but for building your network too.