1. Be Loyal
I can't tell you how many times where I thought a friend was betraying me or when I questioned their loyalty. But The Vampire Diaries shows us that you need to be loyal to your friends to survive. Bonnie really shows us the true meaning of what loyalty is.
2. It's all about the heart; love knows no age
This one is for all you Damon fans. Yes, Damon can be a bit ruthless and manipulative but he does have a heart. Elena Gilbert just happened to find it. Through all 7 seasons we see Damon's transition from a serial killer to someone who protects and loves. Even at his most vulnerable moments, Elena saw through his evil ways and loved his beating heart.
3. Running away never solves anything
Katherine does the best explaining this one. For over 500 years, she's done nothing but run from her problems. Every chance she gets, she is on the move. But what does she learn in the end, all she had to do was face her demons. But since she didn't, she had to suffer the consequence. So from now on, don't run from your problems, they'll just bite you in the ass later on.
4. It's okay to cry
Elena Gilbert best represent someone who lost so much but she didn't let that stop her from becoming stronger and a better person. Elena lost more than most people yet she still stood strong till the very end. She taught us that it's okay to cry. That bottling up your feelings isn't the best way to go.
5. Just because they're gone, doesn't mean they're gone.
Caroline had lost both of her parents and that broke her more than she thought. She even turned off her humanity when her mom died. But just because they died, doesn't mean that they are really gone forever. They still exist in your heart and in your memories. You just have to be open to finding them and learning from them to become stronger.