Tape off the soles of the shoes and anywhere else you don't want to dye. If your shoes have laces, remove them.
Use Sharpies to draw designs on your shoes. Draw a swirl design, or stripes, or anything else you'd like. Remember to put colors that will blend well next to each other.
Finish drawing on the entire shoe, leaving some areas white. You can add more color later if needed.
Use a dropper to drop alcohol onto the ink on the shoes, starting on the lighter colors. The colors will start to bleed and blend in the direction that the alcohol moves on the shoe.
Continue dropping alcohol until colors are as blended as you'd like. Colors will look VERY bright while they are wet, but will soften a bit in intensity when they dry.Pay attention to the tape; as it gets wet it may get loose, so keep a paper towel handy to dab up any excess ink.If you want more color on your shoe, wait about 10 minutes until if feels dry and add more color, then drop on more alcohol.
Remove the masking tape and wipe off the soles. Some color may bleed under the tape, but if you are careful you should be able to keep the soles mostly white. Allow shoes to dry completely (24 hours) before wearing.