The basic problem one often hears people say is that bleaching result can differ from one's expectations and that don't bleach your hair because it will turn white. Well, this happens if you bleach your hair for more than the required time. If you want to save the hassle of dying your hair and then bleaching them again, you should make sure that it is not left on for too long.
Bleaching lasts longer than hair color but you have to apply it the right way. You guys can watch a tutorial on youtube before applying the bleaching for the first time. Another advice for a beginner would be to visit a hair stylist and ask him for advice.
Bleaching is not easy to get rid off and it would always be a good idea to perform a strand test before proceeding further.
If you have no experience in bleaching, the probability of getting it wrong are pretty high. So it will be more appropriate to visit a professional. It could be cost you more, but it would save you from the inconvenience caused by your erroneous bleaching.