Are you the type of person that writes detailed comments on people's post of do you just write that generic crap like "Great post!" "Good share!"
The first thing I do is go to https://app.buzzsumo.com and type in a keyword that is relevant to my niche. For me, this could be "spirituality", "Buddhism", "New Age", etc. For you, it might be "marketing", "SEO", "Fly Fishing", or whatever. In the results, there will be blog posts that have ranked well and been shared a lot. I'll use this information to generate blog post ideas that seem popular and I'll create a list of topics. I usually have around 30 - 60 topics in my list. Next, I'll begin writing an article for each topic. Each article gets scheduled for posting on my blog, one per day. Once I have about a month of posts scheduled, I can sit back and begin working on my next round of posts without feeling rushed or overwhelmed. Generating high quality content on a niche blog to engage your readers is not as difficult as it may seem. It just takes a little work! This will at least give you an idea of what to write about. If you end up hiring someone else to write for you you can give them examples of the content you want written. Hope this helps!
Don't write crap like great comment! Write like you are in 1800 when there are no blog and you got a letter and you need to reply. I know the 99% can't do that, but ignore the losers and be the 1%
Your comment should be inline with the content. It means you have read it and you are not just there to get backlinks. It should be reciprocal for you and the blog to have a win-win situation.
Make comments should be relevant to the content, it's better if you comment on it in a professional and depth
Your comments should be not only relevant to the content, but at the same time very informative and useful