Personally I think too many people “stress” about writing a proof argument. And I think that there are a number of people who want others to think that they have discovered the “magic” formula. There is no magic formula and it’s not as difficult as one thinks. It takes practice and more practice and little “magic.”

Here is my take:

Conduct a complete search of all relevant records that an experienced researcher would expect

• to provide a direct, specific answer to the question
• to provide information, that when combined with a knowledge of the law, culture, and other records, would suggest an answer to the question.

Adequately and completely cite each source used.

Adequately and completely discuss your research procedure if a record that should be found cannot be found. Just “I didn’t find it” is not enough–what records were searched (online, microfilm, courthouse, etc.) and how they were searched (what names, search terms, etc.) needs to be a part of this “can’t find it” discussion.

Consider all possibilities–not just the one that “fits your notion.”

Clearly discuss why certain possibilities are not supported by the records. If there are other conjectures about the persons involved that run counter to your conjecture, clearly state (with supported reasons) and analysis, why those other conjectures are not supported by currently available information. Do not simply discount them and do not simply ignore them. Doing so may indicate to others that you’ve not adequately researched the problem. 

Clearly state your assumptions. If you use a marriage record as evidence that someone was at least a certain age when they married, make certain you know what the statute in effect at the time said about the age of marriage.

Do all that and you are well on your way.