I am in the process of working with a team to author a NonProvisional Patent Application with the USPTO.
If I want to keep my options open for a
EU Patent, what must I do / avoid?
Have you filed a provisional application?? before, if not file a provisional application, as a provisional application gives you an additional 12 months for you to file a Non provisional application and protects the priority date for your patent.
Regarding keeping an options open for EU I would suggest you to file a PCT application as EU and US both are WIPO member's this gives you additional time of 30 months from the priorty date eg: If you had filed Provisonal application on say Dec 24, 2018 in USPTO and before Dec 24, 2019 you had filed Non provisinal application in with PCT you have a time till Jun 24, 2021 to decide to file in Europe or any other PCT participating countries.
Right now, your options are open. But, if you publish the invention they may close, as unlike the USA, the EPO has a very limited grace period for filing a patent application after publication.
The Paris convention says that if you file in one treaty country, like the USA, you have 1 year from the earliest such filing to file in another treaty country (like the EPO - european patent office). PCT is a way of extending the deadline.
However, you need to make sure that what is in your document is suitable for european practice. In particular, the EPO expects literal support of the claims in the specification of the application, and will not allow you to cherry pick from the specification to create new claims if needed; this is called inadmissible “intermediate generalization”. The EPO is just as strict when it considers the priority (provisional) document. This means that if you do go the provisional route, you should probably make sure to have the claims you will later want in europe, already drafted or risk not getting the priority date. If your existing provisional is not up to snuff, file a new one with added material, suitable claims and any desired fall back positions and file PCT or EPO within 1 year of the first provisional.