I ditto what frank (wegot5kiz) said : never go to bed mad at each other...
Someone ( I*think* it was our pastor or my mom) told me and my dh this shortly before got married and I believe its probably the best marriage advice I've ever been given....

One of my others-- and this is not so much advice, but rather something I try to keep in mind while shopping : if I *think* I want to buy something (anything from clothes to shoes to snacks, dinner out, etc and other non necessities) but am even a little unsure, I tell myself that if I still want it in 24 hours, I can always go back and get it (if I can afford it)..... Seems to work almost everytime for me