Every single artist has a bag of tricks. Here are a few of mine.
A quote that resonated with me from the first time I heard it was "the secret to creativity is knowing how to hide your sources." It's up for debate who said that, but the main point is this: we all have influences. We all tend to want to create like the artists we admire, and that can take all sorts of forms. A song can inspire a painting. A painting can inspire a play. A character from a play can inspire a novel. A novel can inspire... you get the idea. The trick of hiding your sources, though, is all about knowing how to riff off of some else's ideas without leaving a trace.
Think of how many pieces of art or tattoos you've created that were originally inspired by the feeling you got from a song or a movie. A painting you did that was directly influenced from another painter. Lines from a movie that inspired your lyrics. It happens all the time. And if you see that, you can run with it. The trick, of course, is hiding your sources. Taking that inspiration, taking that composition that you love, taking that melody that you want, tweaking it enough to make it yours, and then moving along.
Another trick I use pretty often is a tool that has helped me learn new styles or media very rapidly. Similar to "hiding your sources", a quick way to learn to do something is study the work of other talented professionals, but to pretend in your mind that you did the work yourself. Now the question is easy, how did you do it? This has worked for me in the digital industry, with painting, and most especially when studying tattooing.
Do yourself a favor and go to the nearest magazine shop and pick up a quality tattoo magazine, or if you're a different type of artist, go find some work by an artist you look up to. Now, just pretend that work is yours. All of it. Pretend every stroke, every color, every line is something you already did. If it's music, pretend that guitar part or those lyrics is something you wrote. Once you can feel that the skill is already yours, the rest is simply reverse-engineering, or figuring out how something was done from a finished state. The important part here is studying that work, not just looking at it like it's yours. Study that piece of art until you know how you did it from start to finish. Respect the process the real artist took to create it. Understand that if you want to be at that level, it requires the same hard work from you. And once you accept that it will take hard work, once you study it and understand it, you then have the mental tools to do it yourself.
The last trick I'll mention involves something you might not be willing to do. I'm going to encourage it anyway.
First, find a place where you can be alone. Others might get pretty offended if they see you doing this, and you'll definitely have to explain yourself if they find out. Next, put on some cartoons, preferably cartoons you grew up with (I personally enjoy Rocko's Modern Life, Doug and Kablam!). Next, pour milk over a bowl of your favorite cereal (a color-changing spoon works best here). And finally, pull out a pack of crayons and some blank paper. Now have a blast.
I cannot stress the importance of the last trick when it comes to creativity. You may think I'm being dumb, but re-finding the creative child inside you is your first step to breaking many of the bad creative habits you have, and it opens up a world of imagination and goofiness you know you miss. Don't laugh and don't thank me, just go do it!