What Santa Maria said
Hair needs to be neat and plain . Short is good , geometric bob, longer ok as long as it's blunt cut, no floaty layers
Hair colour needs to look natural , no garish highlights or roots
Ditto make up , needs to be a natural look (not necessarily no make up )
Accessories should be few, simple, bold and expensive looking . Nothing "cute "
Plain nail polish only and no long talons
Shoes should be flats or chunky heels. No stilettos, courts
Socks, bare legs or opaques only. No thin tights
Nothing " pretty " or " girly " . No frill, tiny florals
Fabrics and shapes should be structured , perhaps slightly oversized but not baggy .
Doesn't need to be black, another dark neutral such as grey or navy ok
Quirky shapes, classic with a twist
Nothing too tight, no cleavage, not too much flesh , no short mini skirts ( unless with opaques ) , nothing " sexy"
IMHO age is no barrier to carrying off this look, it works great on women even in their 70s. But the structured loose fit can make you look a bit heavier, so IS a challenge if you are bigger than a size 18 ish, unless you are very tall .
It's great on petite women as long as they are slim .