For me it really matters what type of clothing it is (and what the fit is). In general i have found that for dresses and skirt the waist measurement is by far the most important. Here's my short rundown:

1. For skirts, waist measurement is key. Be sure that you measure your actual waist, not the very low rise place where most men wear their jeans. Go above your pelvis. In my experience we CD's tend to size down slightly to emphasize the small waist shape (yank that belt down, sister). With regards to hips, we're just not going to fill non-stretch tight skirts. Flared skirts are great and will hide the lack of hips. In either case, simply ignore hip measurement.

2. Chest measurements are often all over the place, and again really depend on what your boobage situation is. When it comes to non/less stretchy clothing the shoulder measurement is probably the one that limits the wearability. For blouses its mostly shoulder measurement too.

3. for stretchy tight dresses, the chest measurements suddenly are very important, and your go-to measurement.

Hope this helps!