I'm not a big fan of the "breasts so compressed they turn purple" look It's nice as a fantasy and to look at, but in performance I always worry that placing that much force on the tissues will result in cysts forming later.

And besides, the breasts I have to work with on my sub would not stay on even if I tried. Instead I prefer to bind breasts in a web much like the picture below. That way I can just throw one of my dress shirts on her and we can go out. I also don't have to worry about checking her too often to ensure that she's OK.

the other way I've done it, and it took a lot of time an patience, not to mention about 125 ft of robe was to tie a 7 part 5 bight turkshead around her chest. We did it in red rope and it was stunning. She said it felt like it was writhing over her skin the whole time.