It takes a lot to build on something you think you know and then making sure you create a dramatic story.  Influenced by real life, art should be thought provoking.  Finally establishing a reasonably seamless identity within a movie is also a task that most audiences, if done right, just take for granted.

Having a background in studying the classics has helped me make decisions that actors appreciate.  If the story is compelling, then a rich character can have many choices within a wardrobe.  It is a thrill and a serious art form that most Producers understand.  It also is one of the last to get budgets that substantiate your work.  Hence, it is a gift to be able to work with a good script and you have to listen to the collaboration of the rest of your team.  Good advice to younger and up and coming costume designers' is to start by making costume design plates.  Distort the images of the models because it distracts your reader in showing this.  And be willing to merge to the ideas of the Production Designer. 

Although, I still think you have to stay strong to your decisions because you are authentically thoughtful in your creative process, skill and education.  You must also be willing to intelligently support your ideas for your concepts but stay professional.