There are periods where I have lots of time to be in the studio, when I'm in a groove and the ideas keep flowing. I know where I'm going with a project, what my next steps will be, and the entire process feels right. Then there are periods when I'm away from the studio for days on end, and other areas of my life require all of my focus and creative energy. After a spell like that, I will often return to the studio, sit down at my table and draw a complete blank. I'll find I cannot get my head into the space where all my ideas and inspiration incubate. I've learned recently that trying to force the flow usually doesn't work, so I'm developing a system to combat the "artist's block".
Instagram, Pinterest and my growing library of art books are good places to start. I follow painters, mixed media artists, printmakers, fiber artists and galleries. Seeing what other people are doing will often get the juices flowing, and will even help generate new ideas sometimes.
The other thing that really helps - and this is a trick I learned from Bob Siegelman's Figure Drawing Intensives (highly recommended) - is to do a series of quick, small sketches. I try not to overthink the marks I'm putting on the page, and I try not to linger over any individual sketch. Rather, I like laying them all out on the floor as I go so I can view them as a series. I think this is akin to warm-up exercises before a workout. It gets the muscles working in preparation for the more intense stuff.
Last night I did a series in charcoal and graphite, limiting my color options so I could focus solely on line, composition and texture.