Jake Parker talked about this in a YouTube video a while back. He said our minds can only put out what we put in, think of them as "Creativity Banks". If you keep withdrawing without adding new inspiration or ideas, you'll go bankrupt. (At least, that's how I understood it.) I suggest going on little inspiration sprees. Just look at some of your favorite art/artists' works, study them. This fills your "bank" or "library" in your brain, they're your resources. I personally print out art I admire and tape them in a notebook, that way I have access to some references even when I don't have electronics or wifi. This also allows me to trace them if I need help with drawing hands or anything of that sort. I have a 100 page notebook almost completely full, and I use it almost every night. (It also has references for characters I like to draw, like Sonic, in case I forget what they look like.)
Another tip I'd give you is to visualize what everything looks like. In your brain, you may be thinking "I want to draw outer space with a cool bird astronaut. Go hands, draw!" But your hand doesn't have all the details!
- What kind of bird? Is it big or small? Is it big or small compared to space? What color is it? Is it a boy or a girl? How does the spacesuit fit the bird? Does it have a spaceship? What does that look like? Where in outer space? Do you want me to draw in all the black space? I might get tired... Can we see earth in the shot? Is he floating in space, or just on a planet? Is this in perspective? What kind, one point, two point, three point? Is anyone else in space with him or her? Is the focus bird or space or...?
Your "hand" is left filling in a TON of blanks, and now you're completely discouraged because the drawing looks like this:
...Instead of this:
(These were made in paint, and I was trying to go fast. Please forgive the ugliness of the "better" one. XD )
So, to help prevent this, you need to visualize. Before drawing, start with a general idea, say the "Bird in Space" thing. Think for awhile. Go through any questions you have (like the ones listed above) and answer them as best you can. Have the clearest image in your mind possible. Then draw it. You could even sketch it and redraw it if it's for a project you have to turn in or anything.
I hope this helps!