When should I use "tu" and when should I use “dumneavoastră”?
"Tu" if the informal form of “dumneavoastră”. "Tu" creates a certain level of intimacy and should be used to address people you know well or who are of the same age/rank. “Dumneavoastră” should be used to show respect for people who you just met, are older, or have a higher rank.
What is a piece of advice that I can use to become a better writer?
Do not rule out readers. This means that a good writer explains concepts that some readers may not be familiar with and provides specific examples so that readers can envision and better understand his/her ideas. Keep your target audience in mind while doing this.
What is the scope of a college admission essay?
A college admission essay gives you the chance to let your personality shine through. In order to stand out, the essay should be used as an opportunity to show what makes you unique. It is a good idea to have someone else proofread it, but make sure your "voice" remains. Do not use language that is too formal and is not your true "voice". Be honest and use your own experiences and views.