I've learned that I must write almost every day because the muse doesn't just show up; you have to start writing in order for her to appear!
I also will get up and do the dishes, laundry, etc. when I'm stuck on something. Inevitably, an answer will come when I've stopped trying to figure out what to write next. If I'm focusing on something mundane like folding the socks, then the lightbulb will go off and I'll hurry back to my laptop.