Makes A Good Wine Tasting Event

Have enough people on hand to pour (probably a 1 pourer to 15 attendee ratio). Not each pourer needs to be extremely knowledgeable about the wine; some can just make sure that glasses are attended to while others focus on sharing information, answering questions and getting into the details.
Provide good information about the wine through written materials, knowledgeable people on hand or structured interaction between tasters.
Encourage your guests to have an open mind about wine and share opinions after they've taken the time to have several sips and think carefully. A curt dismissal of a wine is often contagious, encouraging other tasters not to take the wine seriously.
Provide food. Without a doubt, having a lot of people imbibing alcohol should have access to snacks or food to slow down their ingestion of alcohol. From a quality of tasting experience, it's good to offer crackers or bread to freshen your palate.
Be responsible about your guests' consumption of alcohol. Ensure people have safe rides home and don't serve people who are inebriated.