Start with the part of the project you find most interesting. If you start with the part you don't like you might quit before you make progress. Where you start is mostly a matter of preference so you might as well choose what you most want to work on. 

Do you start writing GUI class first or reverse?
What are some general guidelines regarding the halakhic permissibility for Jewish doctors to work on Shabbat?  I know that saving lives generally overrides Shabbat, but I am curious about less black-and-white situations that may occur on Shabbat, such as having a shift where one must be in the hospital or be on call, receiving medical training, etc.  Also, in a practical halakhic sense, are there any situations in which the appropriateness of violating Shabbat would depend on whether the patients are Jewish?  I'm sure that these are not simple questions and that there are likely multiple opinions on various issues, but some insight into this topic would be welcome.
