That depends on your own preference. I have a red frame sunglasses and the tint color for the lens is a gradient red tint. Many people say I look more attractive with my red sunglasses. If you don't know what color is good for you, you can ask the doctor to recommen it to you.
In my opinion, you can choose brown or grey for your lens, which are the most popular tint colours. Grey can offe roptimum contrast and block blue light. It also allows the widest light spectrum to reach the eye, so most people prefer grey tint color for their lenses. Or you can choose brown tint color for your lenses, which can go well with your brown frame sunglasses.
I think you can choose what you like. The color of the lenses will not affect how well sunglass lenses protect your eyes from UV light. It is said that brown and gray are the most popular lens color because they distort color perception the least. I think you can choose the brown lenses for you have brown frame. But I also think gray lenses can go well with brown frame too. So no matter what kind of lenses you will choose, you can get a pair of beautiful sunglasses in the end.
Skiers and target shooters will prefer to yellow lenses, because yellow lenses can work well in low light and they can reduce haze. If you want to choose the light tint color, yellow lenses are a good choice. Besides, they can increase contrast for a sharper image. And the yellow lenses can match with your brown frame too.