The teenage Dean appropriated the tip immediately and forever. Deciding and simplifying what to wear wherever is cheaper and quicker once you you know what suits you. Dressing becomes a snap, so be loyal and stick with your style. Adding that something extra, or taking it off, makes the outfit appropriate for the particular party and place.
Because, of course, it makes a difference where the cocktail party is: Hollywood, California, Hollywood SC, Beirut, Tripoli or Paris; the Ambassador’s residence or your neighbor’s garden? "When in Rome," so the saying goes. You don’t want to be dramatically different than everyone else unless you can handle it. For example, a man does not wear a motorcycle jacket when he attends a soirée at Charleston’s Yacht Club. Men there wear the proper uniform of khaki pants and a blue blazer. The Dean once knew two young American beauties visiting the south of France who were assured that everyone, absolutely everyone, went topless to parties at a certain place. Perhaps a little naïve, they showed up appropriately undressed to a party filled with elegant older couture-covered guests. Still embarrassed decades later!
Dressing comes down to the first impression. What can a first impression tell us about someone whom we only met for a moment at a party? Of course we all know human beings are complex and contradictory, but you don’t have to live with someone to sense immediately if you want more of them or less. The package of you starts with eye contact, the smile and what is draping your body. Identify what you want out of the engagement. Something, or nothing? There to sip one bourbon, or to possibly meet your next business associate or romantic partner? You don’t want your clothes to get in the way. A woman does not want to be so flashy others are distracted from substance, but neither does she want to seem too dowdy.
Figure out your primary assets -- cleavage, neck, arms, hair -- and choose cocktail attire accordingly. For your own engagement, you will need to move, sit and stand. As a guest you can swan around or sprawl on a sofa as you wish.