Choosing flesh-colored underwear is the best match, because bridesmaid dresses are thin and translucent, especially when wearing white or light-colored dresses, red or black underwear can easily leave traces through the dresses.
It is wise to choose underwear without suspenders, because many dresses are strapless and backless, even invisible suspenders will leave traces.
Chest stickers are more comfortable than bras, and can be attached to the chest without straps and shoulder straps, so you don't have to worry about leaving any marks on the wedding day, especially when wearing a tube top dress.
When wearing a traditional bra, first put your arm through the cuff, then fasten the bra, and finally adjust the shoulder strap to make it fit the shoulder completely.