In my opinion, there should be a true relevance between the old literature and the new. So, maximum or minimum number of personal literatures to cite should not be a militating factor as far as the issue of relevance is concerned.
Article topics are often the combination of about three more general areas. I wouldn't self-reference more than one publication in any of these areas. Thus I would limit self-referencing to about three at most.
From experience I will say there is now right answer. However, you need to take a number of things into consideration: the targeting journal, type of paper/report/thesis, area of research, etc. If you a reviewing a well-established area of study there will more references than when reviewing a new area of study. However, moderation must be exercised in either case. On one hand if your references are too much as an editor I will be wondering if you just saying/repeating what other have done, than making your own academic or original contribution to knowledge. On the other hand if your references are fewer than expected readers, most especially editors might be alarmed that you may be plagiarizing others, therefore skipping references.
If further assistance is needed please let me know.
It is not a bad practice for a researcher to cite his previous work. This is a show of consistency and continuation in the topic.. I am not sure if there is a limit to the number of self-citations, but of course, you can cite your previous work from which you have taken, or want to discuss some results, in your new article.