Refinery29 is a great site, and they have recently published some DIY nail art tips and tricks. Like me you might want to do it at home yourself. I particularly love the graduated nail colour instructions (the second one down) which i am trying right now as a matter of fact. I was a bit heavy handed on the sponge dabbing section, but hopefully i'll get it right when i do my next hand... will post results.
Here is the full article: http://www.refinery29.com
"Directions: Apply the base color, and wait 'til dry. Pour a little bit of dark polish onto a hard, throwaway surface (we used a CD case) and dab a little bit at a time onto the foundation sponge. Using short, quick strokes, pat on the dark polish layer by layer, focusing on the ends of your nails. Before completely drying, use the topcoat to blend all the colors together. Voila! Ombre nails without a spraygun!" refinery29