No, it's not rude (i've done it in the past). I tell my stylist exactly what I want because 1) it's my hair and 2) if they jack it up, they know I am not paying.
But seriously, don't let anybody feel that they have any kind of power over you (be it relationships or hair gurus) because they will tend to take advantage of you. If she sees that you are 'meek' she will more than likely try to overrun you and give you HER ideas for your hair when you might already have a style in mind. SPEAK UP! Trust me, it's not that hard. Start off by asking her if she has a problem with you bringing in your relaxer... if the answer is no, than tell her exactly what you want done to your hair. If you prefer rollers as opposed to getting your hair blown out, let her know. If you don't want the hair curled/flat ironed and just wrapped in the doobie let her know as well. If you don't want your hair trimmed after a relaxer LET HER KNOW. That way, when it's time to do your hair she'll already know your wants and will more than likely respect them.
Good luck, even tho i doubt you'll need it.
