The simplest method of all is to add some ribbing, which is what I've done in my most recent design (not written up yet, or posted to Ravelry).
A variation of this, which I haven't yet used, is to use cables at the waist to draw everything in, a method even more effective than mere ribbing, since the latter inevitably has a tendency to stretch out over time.
Waist shaping can be subtle, meant to hide discreetly, without interruption of a colour pattern, as in Trellis.
You have no idea how much time I spent figuring out how to place the shaping so that it wouldn't interrupt the fair isle designs in any noticeable way. At times like that, I definitely feel the inadequacy of my brain!
Shaping can also hide discreetly at the side seams in plain old stocking stitch as in Valentine, my first published design.
There's no rule that shaping has to occur on the right side of the work. In my Downton jacket, I wanted to have a purled seamline on the right side, so I used double decreases worked in a line of knit stitches on the wrong side (except in the sleeves which were worked in the round and forced me to learn about the purled double decrease!)
In Wakefield, the waist shaping occurs discreetly, but in four points in the front and back, not at the sides. In Aran designs it's easy to work shaping into the background stitches surrounding cable work.
See how the panels get narrower as they move up the body?
Finally, shaping can occur right in your face as a design feature. That's what I'm working on now in my DSK project, but I'm not ready to show it off.
BTW, I only noticed yesterday, after reading some other blogs (Natalie Servant's and the Yarn Harlot's) that I'm working on this at the same time as other spinners are participating in the Tour de Fleece. Good timing, even if accidental!
The last point I want to make has to do with where to place the shaping; this is of particular interest to anyone whose height (or lack thereof) means that they might have to alter the length of a garment. Waist shaping generally looks best when it's centred slightly ABOVE your natural waist.
Hence, the reason slightly high-waisted sweaters, like Brookline, look so attractive on a variety of figures, both young and old(er).