I started off by picking three sets of three colours, a combination of an earthy tone for base, and two brighter tones:
Mint green, bright red, bright blue
Grey, yellow, green
Beige, pink orange
I painted a base colour on my nails using the earthy tone, and then when that was dry I did a few stripes using the bright colours. After this, I used the bright colours to do some dots.
Then, on all of the nails, I used black and white to do some dots, arrows and stripes.I did this all freehand, so my left hand (I'm a leftie!) looks a bit messier as it was hard to try and get the patterns on neatly, overally though, I think this works!