I am mainly interested in decision-making and details of product UX. Basically answers to questions like...
Do we build out this feature? If so, how should it flow?
How important is this new form style versus the default textbox style we have right now?
Tips?
In a startup, that's all about customer development. Steve Blank has a book and a lot to say on the topic. http://www.amazon.com/gp/product/0976470705/ref=as_li_ss_tl?...
If so, how should it flow?
UX is non-trivial you will have to spend a lot of time learning about it. I always recommend Don't Make Me Think as a starting point. http://www.amazon.com/gp/product/0321344758/ref=as_li_ss_tl?...
How important is...
There are questions that can be answered by understanding UX patterns and anti-patterns. There are also questions that require A/B testing. When in doubt, test.
However, UX can also suffer from premature optimization. Just like in writing code where you wouldn't use a big array when you need a map, don't ignore UX, but don't try to answer details until after it is working or you could find yourself bike shedding instead of shipping.
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