Many things,
1. Hold relations together, because sometimes a simple crack is enough to break them apart and then you just try to connect the shattered pieces of relationship and try to join them, even though you know it isn't going to work.
2. Don't just keep on thinking about the things, just do them. Life is simple, we complicate the things.
3. Cherish and love the people that are around you, don't waste the moments of love, because they never return.
4. You are going to live a really interesting life, provided that you 'live' it. You will face many obstacles, setbacks but at the same time you will have many happy moments, moments when your friends will toss in the air, but live them, enjoy them.
That's enough, I became a little senti.>_<