This isn't strictly advice for writers per se, since it's a collection of posters for first-year design students from graduating seniors. Still, when I browsed it, it seemed just as appropriate for writers - or any creative person, really. The advice ranges from the practical ("finish what you start") to thing that help spark a muse ("go outside") to the kinds of things that keep you sane and able to keep improving in the face of critics ("ignore them both"). Sink In Slowly
You might find something that resonates with you. Since they're in poster form you can print them out and put 'em up on your wall or refrigerator.