Whatever you do, "He" shouldnt be wearing his "best" vest and pants, a real turn off!!!
As previously stated, Clubs sometimes have Mottos (red/white, or christmas, etc, etc). Best to check if there is a certain Motto or dress code on the night.
For the ladies lingerie, sexy dress, whatever you feel comfortable and "sexy" in.
For the man, a suit trousers, good shoes and shirt, or variations thereof
In most clubs, the Taboo is "feinripp" Underwear, Jeans or flip flops and bath towel.
Enjoy your visit.