You will need:
Polish:
White, black, and a selection of bright colours. Remember: you want a contrast.
Equipment: A cotton bud to swirl the colours with. A cotton bud or a paintbrush dipped in acetone for corrections.
Begin by cleaning and buffing the nails, and applying a clear base coat.
1. First, paint on a base layer of white.
Apply two coats. This will allow the other colours to pop brighter.
2. Next, take your first accent colour, and blob it on randomly.
3. Continue with your next accent colour.
4. Continue the same method with your remaining colours.
As you can see, we ended up with a white base, with blue (two types), pink, orange, green and yellow accents.
5. Allow to dry briefly, and then cover with one coat of black.
This will seem a little daunting, but it's OK.
6. Allow to dry briefly. Next, dip a cotton bud in acetone.
7. Roll the bud down, and then up the nail to reveal the colours beneath.
Use plenty of cotton buds, to avoid colours mixing.
8. You can also dab, to create a mottled effect.
When you've achieved your desired effect, allow to dry before adding a topcoat.