Do you try clothes on before you buy them?

I am terrified of online shopping, and always try thing on in store, buy in store. Because being short and curvy, I NEED to know it looks good before I invest! And yes, I am a teenager, which is why when a friend of mine spent $600 ish NZD on clothes in one day, in store, and didn't try anything on, I was horrified. But she just said she'd return whatever didn't look good! The idea seemed ridiculous to me, and yet it's a growing trend amount my peers. Those who do try on clothes in-store usually just go home and purchase it offline thinking it is cheaper and forgetting about shipping and taxes and exchange rates...

What do you think of these new trends??? Would you buy things without trying them on, only to return when you don't like them? Have you bought stuff online after seeing them in-store because of costs?