Ok well to start it depends on the tie. If you want them to be dressy dress them up with a jacket and or a nice shirt. If you want them to be professional dress with a suit. NEVER where a tie that has a joke on it unless you want people to think your on your way to a beer party serving hamburgers. (no fence against beer & hamburgers)
you can be dressy without a suit (it looks bussinessy)
its more about what you where with it!