Be a dreamer. Set lofty goals. But no matter what the outcome, stay grounded. Remember your roots – where you came from and who your true friends are.
As you gain success, popularity, and prestige, people will treat you differently. It will feel good. But just like there are bandwagon fans for sports teams, there are people that will jump to support you when everything is going well and run away/speak negatively of you when things are going poorly.
No matter where you are in life, always treat people with respect and never compromise your values.