Strapless, backless and halter all photograph beautifully. They behave very differently once you are standing, dancing and reaching for a drink. The variable is not the neckline itself but where the weight is carried. Strapless relies entirely on fit through the ribcage. Halter shifts the load to the back of the neck, which is secure but tiring. Backless usually depends on a boned or structured front. Knowing which of the three you are buying tells you whether you will spend the night adjusting or forget you are wearing it at all.

A strapless dress needs to be snug at the top of the ribs, not the bust, and it needs a fabric with some structure or a lining that grips. If you can slide two fingers in easily, it will migrate. Halter necks stay put reliably, though a heavy skirt pulls on your neck by hour three, so favour them in lighter fabrics. Backless works best when the front is corseted or has real internal structure. Tie necks are the quiet winner: adjustable, so you can loosen them across the evening without changing how the dress sits.

There is a reasonable argument that the shoe matters more than the dress on a long evening. A slim stiletto forces you to hold your weight in one narrow spot, which is fine for dinner and punishing for a party. Suede and nappa give more than patent does. A sandal with an ankle strap keeps your foot from sliding forward, which is what actually makes heels hurt. Nude and vanilla lengthen the leg under a maxi. Black under black is the least fussy option and always looks deliberate.

Most people buy the neckline they like in photos and then discover the fit problem at the party. Try it on and raise both arms, then sit and lean forward. If a strapless drops or a backless gapes at the side, no amount of tape fixes it for a whole night. If you take one thing away, let it be that a tie neck or a properly structured corset front will outlast a plain strapless every time, and that a slightly lower heel with an ankle strap buys you the extra two hours you actually want.