Comparison of current work to the state of the art in a (journal) paper
Here are some suggestions based on things I learnt from a seminar on academic writing I got back from just yesterday:


First, what follows assumes that the work you did is truly novel. However, unless you are doing a straight replication of some other work, then there must be some novelty in your work. Your first job is to clearly identify in your own mind what is truly novel, unique and valuable about your work. You need to be very clear about this before you can persuade anyone else.
For the literature review, rather than looking for what literature exists and then comparing your work to the literature, try to write your presentation of the literature to surround what you actually did. Think of presenting the literature like a doughnut. You want to arrange the literature to look like a doughnut with a conspicuous hole in the middle of it--the goal of your article is to fill in that hole. 
In your literature review, it is extremely important to not mention research that is not part of the doughnut. I am certainly not asking you to hide any relevant research (if you try that, reviewers will skewer you); I am rather recommending that you not distract the reviewers with any work that is not directly related to the problem that your article is solving. (And to be clear, the problem you are solving should be what you consider novel and valuable, not more than that.) Your work in the literature review is absolutely not to review all the existing possibly related research; it is only to review the research that is directly related to the problem that you are trying to solve, that is, only research that is part of the doughnut with a hole in the middle of it. Less is more: that is, you do a much better job when you present the least amount of research necessary; too much research that is not directly related will lose the reviewers and make them lose sight of what you're really trying to do.
After framing the literature review section, then go back to the introduction. In the introduction, be sure to summarize in one paragraph maximum the top two points from the literature review that demonstrate that you are filling a real gap in the literature. Note that I recommend that you write this part of the introduction last--because the introduction is absolutely the most important part of the entire article, I recommend that you write it last. I do realize that some excellent writers prefer to write it first, but for less than excellent writers like myself, it is usually best to write the most important part of the article last.


I hope these general tips are helpful.