When you walk through the mall and you see people dressed badly, what is it about their attire that offends you? Is it the fact that the garment is too tight? Maybe it is a horrid fabric design? The fit... is it the fit?
For me it is a variety of things, but usually the fit is the biggest one. If you are a size 12 please do not try to squeeze your boobs into a medium shirt. It will be too tight and will make you look worse. A size 12 is not bad, hell I am a size 12 at least 3 weeks a month. What you have to understand it that showing everything doesn't make you more attractive it will likely make you more noticeable, but not for the reasons anyone truly seeks out.
Small children want to please people, so they act out. When they do bad things they get into trouble, when they do good things they get praise, and this is how we conform their behavior. Fashion is the same thing. Where what looks good on you and you will be praised. Where what looks bad and you will be ridiculed.
I wanted to talk a little about body shapes and how to select a pattern for your shape. Below is a photo of body shapes and their corresponding geometric shape. This make determining your shape a little easier. Be honest with yourself, but don't drink the Kool-aid of magazine peer pressure. You can look like those magazines while still adhering to your body shape.
While I would adore if all the pattern companies used this rubric for pattern selection, Vogue is the only one that puts it on the pattern envelope. You can search through their patterns and see patterns look best on which body shapes. Now they really only use the hourglass, rectangle and two triangle shapes, but you can start to get enough of an idea that you can see what works for you. Have you ever watched television shows like Style by Jury, What Not to Wear, or Love, Lust, or Run? These are stylists helping people learn their body shape. They are not trying to change you into a mold that fits society, they are showing the fashion victims how to be fashion super stars without doing anything but changing their clothes.
When you are selecting a pattern to sew for yourself, keep these in mind or you might not be happy with your outcome. If you are shopping for pre-made clothing, try things on and understand that it is like trying lipstick you can take it off and it doesn't define you. I know sometimes when you put on a dress that you start to feel down if it looks bad, but try to shake off that feeling and realize that this dress was made for a different shape than you are.
I hope this helps and I will be trying to do some posts on each body shape and what articles of clothing typically are the most flattering.