1) Do your homework and check out a few websites for designer glasses.
I prefer looking at a website that has good return policies in case the sunglasses don't fit.
If you're not sure which size to get, ask. Most websites will help you figure out the best fit for your face shape.
2) Buy the sunglasses that suit your face shape.
I've found that round or oval faces look best in wrap around or rectangular sunglasses.
Square faces can pull off any shape. Heart-shaped faces look good in cat eye or aviator styles.
Triangle shaped faces should wear sunglasses with a wider bridge and/or wider bottom of the frame.
3) Ignore brand name or logo, rather focus on shape.
Designer sunglasses and their logos are often overrated, and the styles vary from year to year.
It's better to focus on shape rather than brand name or logo.
4) Know what you're paying for. If the sunglasses are polarized, it will say so in the description or specifications section.
Some pairs can cost more when they have a special coating/finish on them.
Also keep in mind that if your sunglasses come with a designer case, they may charge a little bit more for it .
5) Be careful about buying fake items online.
If you do want to buy replica/fake glasses, make sure to read reviews from other customers first who have bought from that website before .
Beware of websites that only sell replica and fake designer sunglasses.
6) If you're buying prescription glasses online, read the shipping and return policies carefully.
Compare shipping and return policies between different websites so you know what to expect if there's a problem with your purchase.
7) Some websites offer free shipping on all purchases, so it's worth looking around for those deals if that's important to you.