My hair has gotten thinner with age, and all my friends in their sixties--plus a few in their fifties--are saying the same thing. I've also noticed that if I have symptoms of low thyroid I lose more hair than usual.

As for the dryness, what do you use to wash your hair? I've found that moisturizing shampoos, such as Bed Head's Moisture Maniac, pretty much do what they say they're going to do. My hair isn't particularly dry, but it does feel "moisturized" after using one of these shampoos. I've stopped using conditioner because my hair is so fine, but a good conditioner might help you.

B vitamins, including biotin, are supposed to be good for hair growth; I don't know about hair dryness.

Low functioning thyroid can cause these symptoms. I suggest that you discuss this with your physician so s/he can order simple blood test to check it.

Thyroid, anemia, peri-menopause, menopause can all cause dry, thinning hair.

Ditto about B vitamins. I use little Jojoba oil or almond oil after I blow dry my hair. It makes it incredibly soft and shiny. I have also stopped using shampoo with Sulfates. They can be very drying.

Absolutely check in with your doctor.
Beyond that, I wouldn't necessarily load on the moisturizer/conditioners, which can make your thin hair look even thinner.
I have also found that coloring my hair has made it look nicely moisturized, whether I do it myself at home or pay way too much at the salon. And because the hair color is coating the hair shafts, it gives my hair a little more body.
Along with matti's suggestion of jojoba and almond oils, there's a V05 hot-oil treatment out there that I've always liked; it's in a small tube that you set into a cup of hot water for a few minutes, then snip the top and work into your hair.

Don't assume that thinning, dry hair is necessarily a function of aging. Mine was getting quite thin and dry. Then, the commercial shampoo I'd been using for over 40 years was discontinued. I started using a natural shampoo, and around the same time I started taking senior vitamins (per my eye dr), AND glucosamine and condroitin with gelatin (per my gp for my arthritis). Maybe it was one of those things, or a combo of 2-3 of them, but all of a sudden, my hair was starting to look healthier and thicker. Of course, with long hair, it took well over a year for the improvement to reach all the way to the ends, but it did happen.

However, for now, for 'instant' moisturizing--try rubbing a few drops of safflower oil into your hands, and then, starting at the ends of your hand, rub and scrunch your hair, working up to the roots. Leave it in. You don't need enough to turn into Elvis, you shouldn't actually see the oil on your hair, but it does make a big difference. Safflower oil is also a fantastic product to use to moisturize your legs after shaving, or to deal with dry winter hands.

thank you all, i have another question though, where do i buy safflower oil? in the grocery store? ive heard of it but not sure if ive ever seen it. again thanks all for the suggestions, i really appreciate it.