How to do graffiti?

I’m not sure if you mean technically or stylistically but I’ll answer both.

Technically speaking its really not hard: Think of what you want to put up, whatever it is. Find a place to put it. Figure out what kind of paint/ink/whatever would stick best. Apply to surface. Of course, don’t go around throwing up on other people’s stuff – you may acquire enemies rather quickly this way.

Stylistically, if you’re going for the whole wildstyle thing, I’d say the best place to start is to find a jar of peanut butter or some other household product with nice clean letters on the label. Just practice drawing out those letters and others until you get a good feel for their balance. Then start putting it all together into whatever you want to write. Slowly start tweaking it, adding, removing, whatever. See what you like about other people’s work and try to incorporate their techniques.

When you get down to painting, start with crappy paints (ie, the cheapest ones you can find/steal) because you’re going to be doing some nasty stuff at first. After a while start looking at nicer paints – Montana and Belton are popular with many but there’s always surprising finds if you try out other brands. Then you’ll want to experiment with caps: stock caps on Krylon, for instance, give a fuzzy but somewhat thin line. A lot of freight writers use these to get over and around the stuff sticking out of trains. There’s a decent variety of caps out there now that are low-pressure and pretty crisp allowing you to move a bit slower and get nice, more accurate lines. I would stress that in the beginning, concern yourself more with the overall piece and forget about the details like drips, clean lines, etc. All that comes with experience.

Stencils are the hip-now-thing these days so if that’s your game you have a few options. The easiest and most often used is to get yourself a photo of what you want to make a stencil of and then find a photocopier where you can boost the contrast to max (alternatively, of course, you could do this in a program like Photoshop or The Gimp). Print that bad boy out and simply play with cutting out the black parts in a way that the whole thing stays together.

The other route is to do it all by hand. This is a really good artistic exercise because it makes you think of form while considering the physics of the material you’re cutting out of in the end. Whichever way you go, once you’ve got a working piece that cuts well, transfer it to a sheet of plastic (the covers on those plastic things they call “duo-tangs” for school work great) and cut the bits out of that. The reason you’ll want to use plastic is that the paint won’t soak into it and warp like paper or cardboard would.