- Never never never buy a cheapie with a zip anywhere on it. No zippers. Nada.
- Stick with fabrics that are brocade or a thin denim--they're usually pretty tough and don't stretch much.
- I also have the best luck with a front closure--lacing both front and back looks pretty but is a bitch to get out of when you want OUT. I prefer the kind of closure that is a sort of triangle of steel that fits over a little bumpy thing (as seen below) because plain hook-and-eye gets so very battered over time that they get ferociously annoying.
- No straps. No halternecks. They can fit funny or hurt like hell, depending. I get plain overbust corsets.
- Pay attention to sizing on each and every one: different companies, different sizing. I have M to XXL and they all fit me.
When you get it, relace with long bootlaces or shoelaces--top to bottom and bottom to top, meeting in the middle of your back. Lets you loosen/tighten either the top or the bottom much more easily, and shifts less during a day of wear. I have relaced mine with everything from ribbon to macrame cord to paracord over time, and ribbon tends to be too slippy (unless it's grosgrain) and macrame and paracord a whisker too stiff. Shoelaces really are best.
- Spring steel boning is best, but hey, if you like it and it fits the above criteria? Go for it. I rarely pay over $20 for any of mine, and a lot of them tend to be imported from Hong Kong, but considering the wear I get out of them and the battering they take, I'm ok with that.
A GOOD corset may or may not let you bend or sit comfortably. The cheap ones tend to let me move, and since I'm merchanting in them (ie, playing stevedore) they do tend to get rather battered over time; since they're cheap, once you've beaten the snot out of them they are perfect candidates for adding funky trim, patches, appliques, and whatevers. Note the one in this picture-- all the ruffles are because this particular corset has been beaten to within an inch of its life.
You don't have to be wealthy to have a pretty faire costume!