1) No Free Gift (Lead Magnet) to your Intended Subscriber
Times are changing, the days where you collect email address without a unique gift is gone. Exchanging emails for newsletter use to be a good practice in the industry but times is fast changing. It won't give you result any longer. The competition out there is high, as such you must do something unique.
Rather than offer a newsletter, give a book or a course within your niche. It is a system where you give something to get the desired favour in return. You do not have to sit to write a book that will take the next three years to publish.
Select a topical issue within your niche, create an ebook addressing these issues. Your offering does not necessarily have to be a single ebook. You can offer a list of recommended blog post relating to an in-demand topic, a checklist, a course, or even five related ebooks on topical issues in your niche.
2) Unhealthy Placement of Opting form
The sidebar is a common location for an opt-in form, but is it the best position?
This question I often ask when I visit some website. Very little attention is paid to the sidebar by your readers, you will rarely see a blog without a sidebar. For me, I use to take the sidebar as a point of advertisement; I believe the same way many other readers. So I rarely visit sidebars when I visit blogs.
Do not misunderstand me, neither am I underrating nor discarding the sidebar. You can gain a few subscribers from using the sidebar and properly targeting your audience. But the number of subscribers generated will not justify the effort. Your sidebar alone cannot generate sufficient signup.
What will you think of having at least three sign up options for your readers?
You could have the usual sidebar sign up form, an exit pop-up form, and a post based sign up where you offer readers a freebie in your content.