A From a fashion point of view, anything goes, really. The only iron-clad rule is that bras should fit well, which is more difficult to achieve than one would think.
According to one recent American consumer survey, 75 per cent of women polled were unhappy with the fit of their bras. So never buy bras without trying them on first and get the sales staff to help measure you if needed. The right fit gives good support and also looks nicer - no unflattering bulges because your bra is too tight - underneath your clothes.
Also, be sensible with your exposure strategy. A halter top with a regular bra looks ridiculous even on the hippest fashionista. I urge you to consider a strapless or halter-style bra instead.
If you want to show off your bra under a thin or sheer top, pick a nice, presentable one rather than the ratty bra you have had since you first developed breasts. Some may consider this a little too risque but this is not the Middle Ages, and you know best what level of scrutiny you are comfortable with.
Lorna Tio, vice-president of marketing for underwear brand Triumph, also notes the growing popularity of bras that give a peek-a-boo effect when worn with low-cut or backless dresses. Those interested can check out the brand's Party Bra and Seduction collections.