Do's

Choose maternity wear that won't irritate your skin.  Skin often becomes sensitive during pregnancy.  Man-made Fabrics can cause hot scratchy rashes, not something you want when looking for appropriate maternity wear .

Make sure there is expandability with whatever you choose.  You wouldn't want to purchase maternity wear that you'll outgrow in a few months.

Purchase bras with the proper support.  This is a perfect opportunity for you to be professionally measured if you haven't already.  Wait until a few weeks before the birth to purchase nursing bras.

Choose light and airy fabrics that will look fresh and trendy.

Don'ts

Avoid buying maternity wear with big and heavy prints.

Pass on purchasing maternity wear with horizontal stripes.  These will make you appear wider, which is not what you want.

Avoid over-sized bags or purses as that can give you a bulky appearance.

While this is not a comprehensive list, these tips can definitely help point you in the right direction in this confusing time.

You'll get away with wearing your pre-pregnancy clothing through the first trimester.  Just be sure to avoid form-fitting or tight pants as this could potentially harm the baby.  Maternity jeans or pants and skirts with elastic waists will be what you're looking for.

Beyond the fifth month you'll need to don maternity wear.  Single colors work well as they make you look tall and slim.  High-neck tops will add to this look, emphasizing a narrow look.  If you want to keep it casual, you could go for black pants or skirt, or even denim pants.  Cotton or spandex is also an option when looking for casual maternity wear.  When shopping for a maternity dress, a full length will work better than a shorter length as it will add to your height and help frame your figure.