From Quora. Good habits of Product Designers:
Good habit #1:
The best habit of a Product Designer is to... be an avid and pragmatic user of the product you are designing.
Good habit #2: Constantly and continually simplify.
Iterative product design is a lot like subtractive sculpture. You start out with a big block of marble and you have a general idea of the form you want to carve it into. So you get out a bandsaw and start removing huge slabs of rock. Now you have the rough form. This is your initial product specification. Now you get out the big chisels and start to discern head, arm, legs. Now you have your working prototype.
Good Habit #3: Listen to the users.
Constantly get feedback. Read ALL the customer service emails. Drop your defenses and really really listen to criticism. Learn to discern when criticism is valid, and when it is aberrant (this is hard).
Good Habit #4: Iterate. Iterate. Iterate.
Make lots of small and fast changes. Make the versioning cycles as fast as possible.
Good Habit #5: Plan conservatively.
Realise that all great things take time, and that design of new products is truly fret with unknowns. Make conservative and realisable milestones, and simultanously push for more every time you feel slack in the process.
Good Habit #6: Deliver agressively.
In my game development studio we used to have many a late night codefest. One of our engineers was famous for having an intuitive grasp of the state of code. And sometimes, at 4am, he would simply throw down his mouse, and yell "Ship it!" It was ballsy, and it was usually right. Nothing tests the mettle of a product like getting it into the hands of users.
Good Habit #7: Revisit the product roadmap often, and adjust the sails accordingly.
A product is a living thing. A roadmap is a long term plan which ideally translates big vision into material function. As you recieve user and marketplace feedback, you will inevitably need to adjust your roadmap. Do this on a regular basis so that the document stays alive. Reviewing the roadmap also can help you stay on strategic track for the long term.