Maybe you can try some colored sunglasses to lighten your look such as White sunglasses frames.As for the frame shape, you can try a pair of square shaped sunglasses that must flatter your face shape and give your more charming look.
You can try Leopard printed sunglasses. Anyway, I think it is hard to know what kind of sunglasses suit for just according to your description. Why don't you try on some sunglasses so that to find the best looking one? Now, most online optical shops like Firmoo offer Virtual Try-On System that you can try their sunglasses with your photos online.
As to the brand of sunglasses, there are a lot of famous brands. But I think the sunglasses of famous brands are too expensive. I can hardly afford to buy a pair of that kind of sunglasses. Though they are very beautiful and attractive, I still choose to ignore them. Maybe one day when I have enough money, I would have a try. So now, I can just afford to buy a pair of sunglasses on Firmoo. There are various kinds of sunglasses too. You can have a look.
I think bright color is more suitable for people who have darker skins. you can choose pink, yellow or blue frames. If you don't want to be that outstanding, you can choose brown frames. If you can afford a pair of golden sunglasses... I think they are very beautiful, you can have a try too. Once I saw a black girl wore a pair of dark sunglasses. I think they also look good on her. So I think you'd better have a try in any eyeglasses stores first, and then you may find which kind sunglasses can flatter your looking. Good luck!
A triangular face has a very small bottom third and a wide top third. You'd better choose the sunglasses that can minimize the width of the top of the face. So the sunglasses you choose should have a wider bottom. And you should avoid the sunglasses that have a wider top. There are some suggestions for different face shapes. You can have a look at https://www.glassesdirect.co.uk/faceshape-triangular/