It's important that you take care of your hair as it will get more and more brittle and dry, so you may want to consider oil treatments weekly and go for regular hair trims, anyways from every 4-6 weeks on average. Layers are a great idea if you don't want your hair to appear flat and to avoid tangles. If your hair is starting to go lighter naturally (if you're getting gray hairs) you may want to consider getting highlights so that they camouflage the need to color every 3 weeks or so, you can get away with color every 5-6 weeks if you manage to get plenty of dimension from the highlighting of your hair. The general rule of thumb is that skin tends to get paler as we age, so your hair should match, you will want to go about 2 shades lighter than your natural hair color when it comes to coloring and even lighter should you choose highlights. Warm highlights, rather than cool tones, will bring more redness to your face and give you that 'naturally blushing' appearance that young faces have! Wispy short hair is also a good choice, especially if your hair is too coarse to control long or if it is too thin and would become to weak if you continued to grow it out long. Consider getting lots of layers to improve your hair's appearance and give it a more vibrant, youthful appearance.
You will want to stay away from ombre hair where the darker color is on top and then the tips are lighter because if you have gray hair, once it starts to grow in, it will be like a white line where the part of your hair is against the stark dark brown of your hair or black. You may want to consider reverse ombre hair which is a funky trend and can make you appear more youthful and draw attention away from your roots. The roots are basically a very light blonde and the tips are a darker shade of brown, creating a beautiful gradient, this gives almost the appearance of a goddess. Ombre vs. reverse ombre hair is pictured below, if you have gray hairs you want to stay away from ombre (pictured on the left) but may want to consider reverse ombre (pictured on the right) to camouflage your grays.
Make sure that the style appears natural and not too fussed over because anything that appears to 'worked on' can be dated and out of style, if you have long hair go for beachy waves rather than severe curls or dead straight hair. If you have short hair, go for a romantic style rather than a spikey style that is best suited for a 20-year-old punk rocker chic. Again, make sure that you are sticking to a lighter color, especially because darker hair colors will bring out the wrinkles in your face a lot more than light hair colors which will bring light to your face rather than creating uncomfortable shadows. If you are still uncomfortable with light colored hair, then consider just using highlights over top of your darker hair color, but I do recommend at least going chestnut rather than a blackish brown. Remember that layers and soft highlights, mid-length or shorter hair is beautiful to frame your face at this age.