It’s Tuesday and you’re checking the mail when you come across an ivory envelope sealed with a gold medallion with your name and address written in the most beautiful calligraphy you’ve ever seen. Your eyes light up when you see that you (and quite possibly your family) have been invited to share in the wedding day of a relative, close friend, or work associate. Provided that you and the person doing the inviting have a great relationship, joy sets in. Finally, a chance to dress up, get a free meal complete with a slice of cake, and enjoy some bubbly with the newlyweds.

Well, at least that’s part of the deal.

Believe it or not, as a guest of the wedding, you have to do much more than show up and say congratulations. Here are a few tips on what you should (and should not) do as a guest of a wedding or any other shindig.

Do NOT Wait Until the Day Before the Wedding to RSVP: The cut-off date to RSVP is there for a reason. Oftentimes, the couple has to give a final head count to the caterer or banquet hall so they know just how much food to make. So, do the couple a favor and give your yes (or no) to them ASAP. If you must cancel last minute, be gracious and give the couple a call in advance, as simply being a no-show is not classy.

Stick to the List: Yes, you may see a gorgeous knick-knack on sale that the bride may absolutely love. But, don’t let your thoughtfulness turn into thoughtlessness. The couple made the trek through the store scanning their needs for a reason: they either really need or really want this stuff. So, try to stick to the registry. If, on the off chance, all of the items are outside of your means, take the list and find an item on the list, but at a better price for you, or take a hobby of the bride or groom into account and purchase a gift related to that.

Follow the Code: I’m sure that the sundress you purchased looks lovely on you-but, do you think it’s truly appropriate for a black tie affair? The bride and groom have dictated a dress code because you-yes, you-are to add to the overall feeling of the day-and because they said so, really. So, bite the bullet and wear some heels-or, get rid of them-for just one day. However, what if “garden party chic” isn’t in your vocabulary? Simply call the bride, groom, or whoever is in charge of RSVPs (whom you should be calling in a timely fashion to begin with) and sort it out. You could also click here to read a previous post I wrote dealing with the topic of dress code lingo.

Practice Your Table Manners: I’m sure that you already know how to eat properly with a knife and fork. If in the event you don’t, take some etiquette courses to brush up on your skills, as a neanderthal in a dress is not a pretty sight. What about your dining partners for the evening? Chances are, the bride and groom knew what they were doing when the created the seating chart, so you’re most likely sitting among friends that you know, love, and will have a good time with during the meal. If, on the off-chance, they seat you with their obnoxious aunt, creepy uncle, or, if worst comes to worst, your arch-enemy, be cool. Do not use this opportunity to start (or finish) any scores. Be cordial, keep focused on the happy occasion, and keep in mind that when people start hitting the dance floor, you can use that as an escape to either boogie down or score a now empty seat next to a buddy who is seated across the room and away from any seedy characters.

There’s a Reason Why Gluttony is a Sin: In many cases, the wedding may forgo a sit-down meal situation in favor of a buffet. Keep in mind that this style of a meal does not give you a license to over-indulge with five pieces of filet mignon. Oftentimes, the serving are predetermined, so you’re only meant to have three servings of each option-not ten. Besides, piling your plate high with eats and treats will reflect badly on you, making you seem classless and over-zealous about the food. While a free meal is a part of the celebration, keep in mind that you’re here first and foremost to celebrate with the couple. If they encourage seconds (or thirds) be mindful that your eyes don’t become bigger than your stomach-no one likes to see food go to waste.

Bar Blues: There is always that one imbecile who interprets an open bar as an invitation to get completely plastered and make an ass out of themselves at the wedding. Heaven forbid this is a member of the wedding party, a family member of the bride or groom, or (even worse) the actual bride or groom, especially when toasts are involved. You make sure that this person will never be you. Don’t get overly-giddy about the prospect of free liquor. Your alcohol tolerance limit does not magically disappear at weddings, so know it and stick to it.

These are just a few ground rules to keep in mind when that ivory invitation comes in the mail. Keep these close and the couple will be sure to keep you in mind for the next celebration.