... is not in a comb, but rather a brush. While the comb can be useful for parting hair, the main implement to create that smooth look is the "military brush" (so named for its origins). They are much finer than a comb, so they don't leave telltale separation marks. They work by bringing natural oils and proteins from the scalp to the ends of the hair. The best part is that they don't cost much more than a comb if you look in the right places. Sally Beauty Supply in the States sell one that only costs $2.79 (what I own) before tax. Most towns should have one of these stores in the area. Department stores such as Target or K-Mart may carry them from time to time. On the other hand, if you're willing to spend money for the best, that would be an original Kent. If that's too steep, but you still want good quality, Acca Kappa makes two brushes in black and white bristle. They've had a lot of orders placed since the GQ article on them, so be patient. Military brushes are sometimes available in differing softness levels -- I think it's a difference between the light and dark bristled ones but I could be wrong.
As far as product goes, I don't recommend the relatively modern "innovation" of gel. It too often creates a stiff brittleness to the hair, weighs it down, and can exacerbate dandruff. Basically, stay away from alcohol based products and you'll be fine. Murray's pomades and beeswaxes, Brylcreem (which I currently use), and Royal Crown Hair Dressing and Pomade are still sold today and are inexpensive. Some of them may even be available in a department store near you. Beeswax gives the most hold, but is harder to get out in the shower. It's also a bit heavier than light products like Brylcreem. Pomades are sort of in between the creams and waxes. Of course, there are other contemporary hair dressings, waxes, and so forth that do just fine. Look at the labels before buying. Layrite is a somewhat recent invention by Hawleywoods Barbershop of California that others highly recommended to me. It washes out easily, has good hold, and is apparently a good product for those used to gels.
Now, the downside to any of these products are that, if you're like me, it can be easy to make an oily forehead even oilier with some stray product. Just wipe it off with Witch Hazel or water. The advantage is that you won't have any helmet head going on, your hair will be soft and pliable (a plus for your lady/gentleman), and it keeps it healthy. For more in depth (and probably better) advice, I suggest going to SlickVille.com who also have a review of Layrite Deluxe Pomade. They talk about nothing BUT classic men's hair styles and products.
UPDATE: I'm told Imperial Dax Wave and Groom is another great product which has been around for eons.