In short: size down 1 size, and be sure that your hips are not too narrow for this cut. :) If it is a match for your particular body shape (explained in detail further on), it is definitely the very best off-the-rack corset you can get!
Just to give you an idea, my measurements are: underbust 75cm, waist 73cm, high hip (where you can feel your upper hip bone sticking out) 82cm, widest place of my lower hip 91 cm.
This Restyle black cotton underbust is my second attempt at finding a suitable & affordable corset, and my first purchase here at Restyle. According to the numbers on their sizing chart, I should have been a size 22''. But (as of April/May 2018) the sizes do run a little large; I should have ordered a size 20'' instead. I was able to fully close the size 22'' corset right away while trying it on for the very first time.
The first impression was very positive indeed: even though it closed completely right away and made my waist 11 cm smaller (64 cm, which, however, still is a whopping 8 cm more than what the sizing chart says...), it felt no different from just wearing tight-fitting normal clothes. The comfort level of this corset is incredible! But then, the size was actually too big for me; I could fit both hands into the corset at the top and bottom, and the hip "pockets" flared away from my actual hip and could have fitted another pair of hands inside. So I don't know how the proper size would have felt, but probably still comfortable.
As for the silhouette: it definitely gave me cuter proportions than without the corset, but still a very normal and natural shape (except for the exaggerated hips which I could not fill, but again, sizing down will fix all that). Also, probably only due to the bigger size, I found the corset still looked a bit too "tame" and normal on me. You see, I'm looking for a very pronounced, extreme, dramatic contrast and an unnaturally small waist (the maximum waist reduction possible while still being comfy in the corset) for a particular character costume at a cosplay event later this year, not for a daily undergarment (at this point).
That's why I decided to experiment: instead of just going down one size in this one, I now ordered Restyle's CU7 model (same price, colour and fabric too) _two_ sizes smaller, at 18". After comparing all the sizing charts, reviews and pictures here and re-measuring myself 100 times to be absolutely sure, I figured the CU7 might fit my particular body shape (apparently it's called "banana" / "rectangular" or "straight" body shape in English) a little better. According to the sizing charts, the 18" CU7 should fit me around the hips and ribs just like the WH 20'', but with the waist reduction of the WH 18'' (that is, expecting the actual corset to measure at least 1-2 cm more than the sizing chart numbers). Mind you, I'm ignoring the customer service chat lady's advice here - but she only copy-pasted the corset descriptions of this website in response to my question if my idea would work, and even though she re-measured the WH corsets of size 20" and 18" for me, the numbers she gave me were so different from those on the sizing chart, like 10-20 cm smaller, that I decided to just go for it and find out for myself. I know the sizing chart numbers should be taken with a grain of salt, and my theory does sound too good to be true, but I just couldn't resist giving it a try. ;) I'll let you know how my experiment went as soon as the new corset arrives. :)
(of course, this is a solution for _my_ particular body shape, size, and need, so consider your own before deciding which model would work better for you).
Shipping & delivery of this WH corset was perfect, and the corset itself looked exactly like on the pictures. The fabric texture and color happens to be exactly what I need for my costume, but if this corset was for my daily wear under my own clothes, I really wish there was a curvy and well-constructed corset like this one or the CU7 available here also in a nude / soft ballet pink / neutral light beige / skin shade. And instead of cotton, to which your clothes will cling, made of a simple satin _without_ embroideries / prints / embellishments etc, to make it as invisible as possible under even light colored summer fabrics. I would buy at least 1 corset like that every year! :)
In terms of fit, comfort, quality, shape and construction, after comparing different brands and doing quite some research on the internet, it seems to me that Restyle has the absolutely best quality "off the rack" corsets that you can find in this price category. The next best option (in terms of fit and material quality) would probably already be a custom-made corset for 10 times more...
Of course, the very affordable price means that there has to be some compromise somewhere along the way.
Pros: Low price, superb construction, fit and comfort, good quality lacing strings. Modesty panel can be removed very easily.
Cons: made in China (who knows under what kind of working conditions...). Also, the cotton fabric, actually the entire corset, felt a bit "cheap" and flimsy in my hands, and the metal seems to be very low quality, weak and soft. The uppermost loop of the busk got bent out of shape while I took the corset off for the first time (in a hurry, I admit), but it was very easy to bend it back into the correct position with a pair of pliers. I later wore the corset for a second day to find out if it was my fault or the metal's, and I was extra careful while taking it off, and everything went fine, but still, the whole thing feels like it won't survive a few months of intensive tightlacing, unfortunately. But of course I didn't expect to get a 100+€ corset for 45€! :) All in all, I'm extremely satisfied with this brand, and very happy that an option like this exists for people like me.
To conclude my overly long sermon: these Restyle corsets are definitely worth the money! They seem to be by far the best corsets available for under 50 €, and especially if you're just trying out corseting for the first time, go for it; this brand is the absolutely best deal you will find! :)