How do you know your paper is ready for submission?
The truth is that the paper will never be in perfect condition for publication. This is the role of peer review, to evaluate the work from an expert viewpoint. In general, I have seen that after 2 3 weeks and after 4 5 revisions the quality of the paper increases and reach a saturation point where the paper needs an external opinion in order to be improved. If an external opinion is not possible(the paper might be outside a peer domain), then one must forget the paper and to reevaluate it after some time, and then to submit for publication. However, what is more important is the idea and the results from the paper, and not only the presentation form. Also, the validity of the results and the interpretation is very important.