Yes, it will damage your hair, but there's no avoiding it. My philosophy, however, is that your hair does grow back; so dye now and worry later! Plus, most of the dyes used to achieve unnatural colors act almost like a deep conditioning treatment, combating the damage caused by the bleaching.
If you really don't want to bleach don't expect to get the brightest results, unless you're a natural blonde. If you have black hair, you have no option but to bleach. Keep this in mind when you make your decision.
So, apply the bleach, let it set until your hair has lightened enough, and rinse. Follow the directions on your bleaching kit carefully so as to not harm yourself with these harsh chemicals.
Use a comb or brush to spread the color throughout your hair if you find it difficult to do with your hands. Wear gloves during application because these dyes have a tendency to stain the hands and fingernails. They'll stain just about anything, really, so dye with caution!!
Now it's time for the fun part! Sitting and waiting for the dye to take, can be pretty boring, Keep yourself occupied with a book, magazine, or a movie. How long do you have to sit like this? It depends on how hardcore you feel like being.
Forty-five minutes to an hour as a minimum and more is enough if your hair is very thick. Longer the dye sets, brighter the color and stronger the staying power. Some people will wrap their hair in tin foil and shower caps and let the dye take while they sleep at night. An hour or two should suffice if you've bleached your hair.
Some claim that rinsing hair with vinegar or using a blow dryer on your hair before rinsing can help the color take better, thereby making it last longer. The vinegar trick has something to do with pH levels. Blow drying is a way which is worth giving a shot.
Be sure you get all the dye out so you don't turn your towels funky colors! Though, be warned, this might occur no matter how much you rinse, so it's best you use an old towel.
Manic Panic or Special Effects dyes, beyond a doubt, they will give you the most satisfying results. Try shopping at Sally Beauty Supply or Hot Topic to find these dyes in a wide variety of colors. You can also find them at various stores online.