If you have dark blonde or light brown hair and want natural highlights, try lemon juice and water. Using a squirt bottle, add two parts freshly squeezed lemon juice to one part water and spritz on your hair before sitting in the sun approximately 30-60 minutes. Be careful to avoid getting into eyes. While this method takes some time to work, if you apply lemon juice once every few days, you should begin to notice results within a week or two.
The acidic properties of the lemon will lighten up the natural pigments of your hair. Condition your hair well after each application to avoid drying out your hair. While soaking up the sun, don't forget to apply your sunscreen and reapply, if necessary.