Below are just a phases but each phases needs to pass through some tough decision this linked article about what to keep in mind when make decision once to start and progress this process.
In my experience most important aspect of making decision in product engineering is to ask your self 4 questions.
0.is this feasible to do this things now by time,resources, money and priority?
1.by doing this am I making this product useful and usable and adaptable?
2.by doing this am I making this product efficient, secure and scale-able?
3.by doing this am I making this product more maintainable, repairable and manageable/distribute-able?
this are the answers of the questions in order you need to think from 0 to 3.
if answer of 0 is positive than you need to make all other question`s answer positive and deliver at the end.
I have seen a lot of article that go through data gathering and following trend and a lots of other non user/consumer/customer concentric approach.
that what exactly contemporary time problem and that's how market is become more of gimmicky products instead of actual useful or even more innovative products.
by following trends and investment flows only one sided advancement goes in product engineering and that raise the bubble and sometimes even turn into economical disaster.
I hope my this prospects will help to keep simple and ideal when it come to making decision during the Product engineering.
The Wall