Pictures, copy, topics and tags. It's all super important to make sure your content gets noticed on Steemit.
Here's a summary of the posts I've done about this in the past.
I'm no expert, but since I joined a while back I've picked up a few tricks that I want to share with you all.

Pictures

Never post on Steemit without a picture!
Use high-quality pictures and use your own pictures!
If you have to use a stock photo - credit the source. There is this little thing called copyright.

People like faces, they can relate to it and it's engaging.
It's nice to use more than one picture too. Don't put your only photo at the end of the post. I usually write a short summary, put the picture after that, and then add the rest of the content. This way the reader will see the picture when they open the post. If there's just text for a long bulk on top, some might think it's too much to read.

Air

Add some space between things. Use paragraphs and add space under and over pictures. It looks better and the reader isn't overwhelmed with big chunk of text.

Title

The title is one of the most important things to consider before posting.
Be creative, brave and fun.
Don't fall for the temptation to go for the click bait tactic, like something super sensational, if your content isn't.
The readers will be disappointed if the headline doesn't live up to their expectations.

The first sentences in your copy

These are super important because it will show in the preview of your post.
All your potential readers will see is one picture, the headline, and these first words. So choose wisely. Make sure to summarize your post in these first sentences or some way catch the reader's attention.

Tags

Who is your target audience? What tags would they click on to read about?
There's nothing wrong with trying to create your own tag, but at least use some tags that are popular or common. (Only if it's on topic). People will get annoyed if you use a tag that has nothing to do with the content.
Use quality tags, don't be a spammer. Yo'll get more followers if you use relevant tags. Trust me!

Grammar

This is more important than what you think. You want the readers to understand you! Poor grammar can be a huge distraction. Even though English isn't my native language, I make sure that my writing is somewhat correct.

You can use tools like Grammarly if you struggle with writing. Your readers can definitely tell whether you've spent some time on your post or not.

Another great tip is to read the finished post out loud. This way you can notice if something sounds weird.

Engagement

If you want people to engage with your content, you should also engage in their content.
I love food, so I visit this tag often.
I click on "new" and "hot" to see if I find a headline or picture that catches my eye.

Offer value

Not only will this encourage people to share your content, you're also contributing to making Steemit what it is.
A great place for learning new stuff and to engage with like-minded people. (And maybe even people that are very different from you.)
If you've got some kind of special knowledge or if you learned something unique from an experience - share it with us!

Honesty

If you want people to be able to relate to your content, don't try to appear like you're perfect. Nobody is.
Some of my most popular posts include my personal opinions or just self-experienced stories.
Readers enjoy stuff that could also, or have, happened to them.

No spamming

The next time I see an "upvote plz", I'm gonna lose it!
If your content is great or if we have the same interests I'll for sure check your profile and follow you anyway!

Share your opinion

Don't just post something with tons of facts. Add your personal touch.
If you've taken some photos, don't just share that. Tell us where and what it is. What camera did you use? Could you improve the pictures? How?

Be social

Write about something you're passionate about. Ask questions. Be curious. Be genuine. Dare to stand out and be courageous. Also - be friendly. Remeber that you have a reputation on Steemit and that what you post here will stay here. For ever! See this platform as a great opportunity to get to know people all over the world!

Reply to comments

Appreciate the people that took their time to read your post. Be grateful for every reply. Be grateful for your followers. They've spent time on giving you their feedback, the least you could do is reply.

Markdown Styling

Use this cheat sheet to style your text and make headlines and bold text.

https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet

This will make your post more tidy, and it will look a lot mor stylish too.

Additional advice

You don't have to be an expert on what you're writing about, but at least be humble and honest about how much you know.

Have some fun and be a helpful person. Try to encourage fellow members! It's not like if someone else has success, there's no more success left for you!

Make sure that your post has an intro, a main body and a summary in the end.

Read books! Read articles. Read a lot! Reading improves your writing. It's as simple as that.

Not sure what to write about?

I've made this earlier:

https://steemit.com/writing/@susanne/writers-block-here-s-20-cool-ideas-for-steemit-posts

It's some ideas on what you can write about if you have writer's block. Have a look!

Good luck with our writing. Let me know if you need some help or have some questions

Susanne