Social media posts should be like billboards, that readers might take one or two seconds to read. They should be short, easy to read, and catch the reader's eye to make them want to read it. I think of it this way...if it were a billboard on the side of the road, how many people would stop to read the whole thing, especially your top post? That one is like the hook for readers, to reel them in. If it has wording that's difficult to read (either in color or font), no one's going to stop to read it. If it's small, they're going to ignore it. It has to catch the reader's interest and keep them scrolling past the first post.
Every day, I make a 'top' picture post that I pin to my page, so that the 'drive-bys' can just click and move on if they're in a hurry. It has the list of books I'm promoting for the week with my logo and name of my site at the bottom. I then include a picture of some type above the books and logo with my own saying. I do this by the month, so every month, I have to come up with around 28-31 new sayings for the next month. I'm sure I repeat myself, but it's not easy.
I'm working on March's things right now, so yesterday, I went to Pinterest and found sayings about love. I took some of the sentiments and made up my own sayings from that. It was easier than coming up with the thoughts by myself.
Then, I went to Pixabay.com and Pexels.com and got pictures from creative commons, for free. Using Paint.net, I create one posting per day for Twitter. I also post them on Facebook under SweetTale Books.
Then, for each book (I have 59), I've created two postings--one with a blurb and one with a saying at the top to describe the book. On top of that, I've been adding quotes and interesting facts for the day. Thus, I put either three or four posts a day on social media (three on the weekends). At the top of those posts, I add links and other sayings. It helps keep my writing name out there, but it's a lot of work.
I've seen many writers do the same thing, with different posts each day. It's a lot of work, but well worth it in the long run.
Have a great week!