Most Helpful Girl
I'm sure guys like girls who take care of themselves. Because... really. If you can't take care of yourself, how can you take care of your man?
That said, I agree with the advice above. A healthy diet and semi-frequent barber visits are important. If your hair is weak... definitely do NOT straighten or curl it. All you're doing is frying your hair. Some girls get away with it because they have plenty of natural oils that help with the moisture loss when they style it. Also, talk to a hair stylist about different shampoos and conditioners that would be best for your personal hair type. Don't just buy Wal-mart brands that say "For straight hair". If your hair is unhealthy, you need to get something more sophisticated. There are also different formulas that your hair stylist may be able to recommend to repair your hair.
Also! Ask your hair stylist if your facial bone structure would look good with short hair. I have quite a couple of friends who went super short and now look more mature and sexier than they did before. Both of these girls have thin, brown hair. Their hair is healthy though, because they take care of it. It may be scary at first, but if your stylist thinks it may be a good idea, go for it. :)