There are many sayings, quotes, and words of wisdom out there. Here are some that I try to live by.
"Tolerate much, but not intolerance." - By this I mean, be accepting. I may not believe in the same god as you, but I respect your beliefs, as I hope you respect mine. Those who think one group of people should be massacred off the face of the planet are highly intolerant, and therefore should not be tolerated themselves.
"If you can't laugh together, you can't love together." - I learned this when I met my now husband. I was engaged twice before, but the humor wasn't compatible - with my hubby, we laugh at much the same things. If your relationship is all serious, it can cause stress and strain.
"A true friend is one who walks in when the rest of the world walks out." Walter Winchell - I had to learn this the hard way with my ex-best friend from high school. The friends you know you can count on when your down, those are the friendships you should nurture.
Those are the three that I try and live by. There are many out there, and everyone should find or think of words to live by - I find that I can catch myself if I start to be intolerant, and adjust myself, asking why I reacted that way and explore the answer. I like having guidelines for myself - I think it makes people wiser.