Pattern Brand Awareness
One of the best pieces of advice I have gotten is from the book Power Sewing, by Sandra Betzina. You can find more details in this book (I recommend it), but the gist is this:
New Look and Style patterns: true to your measurements (go with your full bust measure)
Butterick and Vogue: true to your measurements
McCalls and Simplicity: run larger. Choose a pattern that matches your upper bust measure). I've had to choose up to two sizes smaller with this brand.
Stretch & Sew and Kwik Sew: realistic measurements
Burda: flattering European cut, also true to measurements