For basic things, books, etc, I like to go to Amazon prime - student subscription is well worth it imo and prices tend to be pretty reasonable/cheaper in-store. I'll get clothes online if there's a decent sale but I like to be able to try it on/don't want the hassle of returning it if it doesn't fit. For stores like H&M or F21 which are huge and aren't super organized in the way they organize their clothing in the store, sometimes I like to scope out what I like online and then find it in store so I can try it on. I wish women's sizing was more consistent (there are even wild variations within the same brand, different cuts are more flattering than others, etc) but for now I have to try everything on.