FTF: Foundation Garments
Any foundation garments you want to wear with your dress, make sure you bring to every fitting. Even if they don't seem to change your appearance dramatically, your foundation garments will affect the way the dress hangs on your figure. Depending upon the design and cut of the dress your options for shape wear will be limited based on what can and cannot be seen.
If you have a wedding dress with a boned bodice i recommend not wearing any type of bra or bustier. The dress already has the structure that you need and another undergarment will just add bulk to the dress. If you have something soft with no structure in the bodice there are several different options depending on the back. One option is to wear a bra that sticks to your front, or sides, so there is no strap across your back. Another is a strapless longline bra; they have a deep V in the back so it wont be seen on some lower back dresses. There are more options to be found depending on your comfort and dress style.
If you choose to have shape wear you can wear whatever makes you comfortable and will not be seen. Stick to colors in white, nude, and blush. Some brides choose not to wear anything under their dress and that is fine too. So, if you choose to wear foundation garments, bring them to your fittings, and if you're not certain which will work best for you bring different styles to the first fitting and pick which one you like.