I changed sizes and I ordered one item in 4 sizes, including a tall, as I did not know my size and the reviews said it ran short. Now I know the sizing, but it won't transfer exactly to other items from the same line.
I used to order one size, then return it and order another, but now I find it easier to just order the items and return the ones that don't work. Usually it's only 2 per order.
I purchase online from stores that I can return to in person, although one is further away than I prefer, as it left my local mall.
I usually look at an item in store, then order it in my size. Seeing items in person allows me to check the color, material, etc. before I order, which significantly cuts down on returns.
There is very little in person in second hand stores in my size around here, so when I'm with friends I shop wineglasses, bowls, serving platters, etc. Fit is way too hard to figure out, so I don't shop second hand clothing online.