First,select the type of the glasses you like,including the shape,the color or the material. Second,try them on and have a look through the mirror . If you canÃ¢â‚¬â„¢t decide by yourself,ask someone to go along with you,they will help you for reference.Or you can ask the salesperson to recommend for you.
It is so easy. If you want to buy a pair of sunglasses online, you can try the visual auto systems. They can put the sunglasses you choose on your photo and then you can know whether this pair of sunglasses fit your face shape or not. And there are all sizes marked on the sunglasses frames in the description. Or you can measure the size of your eyeglasses at hand and then place an order that have the same size as your eyeglasses at hand. The sunglasses will have the similar size as your eyeglasses at hand. Or sometimes they will be a little bigger.
You'd better try on all the sunglasses that you like in any eyeglasses stores or optical shops if it is the first time you are going to buy a pair of sunglasses. There are all kinds of sunglasses in eyeglasses stores. if you don't pay much attention to the price because the sunglasses sold in physical shops are more expensive than that sold online, you can definitely find a pair of satisfying sunglasses in the end. Or you can note down all the information of the sunglasses that you like and then find a pair of similar sunglasses online. This can help save your money. Hope this helped!
I suggest you to have a try in any optical shops if it is the first time you buy a pair of sunglasses. Many online eyeglasses stores will tell you that a difference of within 2 mm in glasses size is acceptable and will not influence the way eyeglasses fit. But I bought a pair of sunglasses online that can't fit my face. They will drop on the ground every time I bent down. And it is difficult to measure your face, so I think have a try in any physical shop will be the best choice for the beginner.
What's your face shape? There are many suggestions for sunglasses for different face shapes. Of course a pair of appropriate sunglasses that fit your face shape will flatter your look. You can have a look http://www.firmoo.com/answer/index.php?main_page=search&k=face+shape&s=. Maybe you can know which kind of sunglasses can best go with your face shape. Hope this helped too. Good luck!