Hats are not normally worn
Any Jacket
If desired.
Avoid Denim.
Designer Jacket
Blouse
Fashionable Top
Avoid slogans and logos.
Jumper
Knit-Shirt
Sweater
Avoid slogans and logos.
Cardigan
T-Shirt
T-shirts should probably be avoided for most occasions as they do not have a collar which is normally one of the defining features of 'smart' dress, but can look smart, for example if worn with a jacket.
Designer Skirt
With or without matching jacket.
Avoid wearing two different patterns for the skirt and jacket - plain goes with anything.
Designer Trousers
With or without matching jacket.
Avoid wearing two different patterns for the trousers and jacket - plain goes with anything.
Dress
Skirt
Trousers
Fashion Jeans
Not suitable for all occasions. If in doubt avoid.
Always wear very smart or fashionable ones, if at all, and always in good condition.
Shoes
Boots
Nice ones of course ;)
Coat
If weather requires.
Jewelry
Including watches.
As much as you want! (Consider your personal security though.)
In General
Wear something smart, comfortable, and inoffensive.
"Spiffy" Casual
Spiffy Casual is derived from the term Spiffy, meaning cool, neat, unique, or interesting and has it's (sometimes ironic) origins in the archaic English exclamation 'Spiffing!'.
This suggests that one should dress up but keep it modern and trendy. A designer suit with a black shirt with or without tie or even something more creative such as mixing a T-Shirt with the suit, or wearing a very fashionable or designer jacket are all good. A lady might also want to consider a cocktail dress.
As always consider the event your are going to and who you are going to be there with.