In every aspect of your life, always make new and unexpected connections between ideas and people, actively explore new fields, go the extra mile to far-flung art exhibits and parties. The wealth and variety of new ideas and influences is just waiting to be explored, raided and mashed up by your imagination. You'll also make some great friends on the way. Bring awesome people together in your domain and see the sparks fly. Regularly and with thoughtfulness.
Novelty is critical in your early-mid twenties (and for life, to a point), but not an end in itself. Seek out new music, new people, art, ideas, arguments. Filter, discard as integrate them as best you know. Your brain is still forming as creating critical new connections.
***NEVER TAKE ANYONE OR ANYTHING FOR GRANTED. They may be gone tomorrow, G-d forbid.
Join a community of like-minded people and help grow it. If none exists, create one. This kind of stability is a great premium when you're young and inexperienced. Find people smarter and wiser than you and learn from them and have them around you often and regularly.
Learn the Old Testament (Torah) REGULARLY - at least weekly or preferably daily, if possible. The lessons in there are more than enough to work on applying for a good, meaningful and fulfilling life.
Don't linger forever on observing yourself and others. Learn, apply, do what needs to be done and move on to the next item on the agenda. Life is too precious to be left to contemplation alone.
Find your soundtrack (classical, jazz, whatever - just classical, actually) and work it regularly to jog and sustain your mind's creativity. Experiment and tweak regularly to evoke new ideas and associations.
Don't let others trample you with their misery, complaints and stupidity just because you're a "sensitive soul" who wants to help. This quickly turns to abuse, even (especially) among close friends, if allowed. If you see it happening, cut it off immediately. It will stifle your own development, when you focus only on other people's problems, not your own. When you're in a better place yourself and have managed to address your own issues, you'll be better suited to help others and more profoundly - from experience and a more solid place.
Don't let others take real, shameless advantage of you. They will, if they can, those types.
When people you know see you, they associate you with an emotion. Do you make them feel good about themselves? Are you the local asshole? Clown? This is the real power to make an impact. Be good to people, make them feel good about themselves (give well-placed compliments from time to time). Be reliable, be consistent. That's how you build a reputation and create good associations with your name.
"A successful person is one that can build a foundation with the bricks others have thrown at them." - David Brinkley