Well, for starters, there are a lot of helpful sites on the web. Every great artist needs a little outside inspiration now and again. First thing you might want to figure out is what style of tattoo you're really into. Are you into traditional? New School? Japanese influenced? That will kind of give you a jumping off point. Go to google and do an image search for "tattoo flash",
"old school tattoo flash", etc. Then you can always do a site search for "how to draw tattoo flash". You can also try looking up various artists who have a lot of flash work on display, my recommendation would be trying out Sailor Jerry's homepage. Tattoo Johnny is another website with extensive flash pieces. You might also think about picking up a few tat mags, like Skin and Ink or Tattoo which have entire sections of their magazines dedicated to nothing but flash. Also, consider stopping into a few local shops, since they all pretty much carry a variety that you could at least look at and get some general ideas from.

As far as flash goes, the best thing initially is just getting ideas or getting inspired. Find a few things that you really like and then make them your own. Experiment with colors and even trying to blend two styles to come up with a hybrid. You can get as stylized or as intricate as you want. Best of all, it's your art, so you really can't go wrong. You're only limited by your imagination.

Hope this helped a bit. Good luck and happy creating!