The key, I think, is to convince readers that the novel element in your paper is in fact important. How do you do this? The threshold is that after reading your paper, researchers familiar with the literature in your area should see the world differently. How to do this varies to a certain extent based on whether you are writing in theory or empirics. If it’s a theory paper, one element would be if there is a problem that people have understood is important but have not known how to solve. If you can make an advance of this type, that will be very impressive. A second possibility is that there is an outcome that, under reasonable assumptions, people had not thought possible. If you can show that this outcome is indeed possible, then this can be very impressive as well. Note, though, the clause “under reasonable assumptions”! One important element of the problem may be to establish that in fact the type of assumptions that you make are more reasonable than those that the prior literature makes (or at least no less reasonable).
An empirical project may involve conceptualizing the problem, waiting for a grant approval, gathering and cleaning data, getting the software programs up and running, doing first runs, writing a paper, issuing it as a working paper, sending it to journals, getting rejections, doing revisions, submitting a final draft, and waiting for it to finally appear. Thus the paper in the issue that arrived today may reflect the state of thinking five years ago! On the other hand, you should expose yourself to material broader than your own research project, for two key reasons. The first is that there may be unexpected synergies between work in other fields and your own inquiries. Many economists have made a career out of exploring just one or a couple of those synergies. Second, by reading some of the best research and by looking at it with the appropriate questions in mind, you can come to understand concretely what the profession recognizes as outstanding research.
Economics, or academics more generally, is not a place for reverence! Read what is being written in your field, recognize the contributions that have come in the prior literature, but do not be awed by it. Question everything. Try to state the arguments in your own words. Do you find the arguments convincing? Are there some lapses in the broader claims that are made? Often these will be the paths open for new and interesting papers. While one should respect prior work for having brought the field as far as it has come,every step forward begins by recognizing the limitations of what has come before. If you look at the prior work too reverently, it will be hard to see these steps forward.