What time of day is the party?
What's the location?
How many guests?
Is it formal or in-formal?
This doesn't mean your thick Christmas scene cable knit sweater to dress up your jeans.
Festive Attire for Women
Add a bit of holiday color and sparkle or beading.
Nice black pants or simple black skirt with red silk blouse or cashmere sweater or sweater set, nice dressy flats or pull out these chic pumps.
Festive Attire for Men
Add some holiday color to your shirt, nice dark dress pants (usually stay away from khakis or light colors), nice leather shoes and socks, maybe red or green holiday pattern.
For evening and for warmth, a nice sport coat and leave the large cable knit sweaters in your closet.