You can go a bit higher than the typical “two inches above the knee” rule, but use caution and don't go too short.  Also, make sure you test sitting down in your outfit before the party to ensure it doesn't show too much when in a chair. After all, no one wants to be worried about fixing

their skirt while their manager is speaking to them at the party.

A higher neckline can be extremely flattering, and it will make a big difference in keeping your look professional.  If your ensemble feels a bit bland, a necklace is a great way to add some pop of sparkle while still keeping it appropriate.

If your party's venue is going to have bright lights, try to avoid sheer fabrics — they may end up showing more than you'd like.