Simple--plan a post-wedding party. Less formal than a reception but still a dress up and dance occasion, your post-wedding party will include everyone you love and let them know that their good wishes are important to you.
Breaking the News
The easiest way to break the news to those you can't invite to your wedding ceremony is to send the post-wedding party invitation very soon after sending the engagement announcement. Sending the invitation early lets your guest know that he or she is wanted and that you thought of him or her immediately.
If your parents are not invited to your wedding or if they can't attend, talk it over with them first on the phone or, if possible, in person. The same goes for your siblings and your best friend. Explain the situation and then let them know you're planning a post-wedding party and would love for them to be involved. Ask for help in choosing the location, favors and food.
An Intimate Gathering
Depending upon the size of your party, you may be able to hold it in your or your parents' home if you wish. This is certainly the most economical solution and will have a cozy and intimate feel. However, bear in mind that you'll be responsible for the clean-up after the party. If possible, plan ahead of time to hire a cleaning service for the day following the event.
At-home parties can be as upscale as those held in a banquet hall. Find out about table, chair, dinnerware and cutlery rentals. Hire a reputable but economical caterer and have music available--either a band if you have the space, or a DJ.
Leaving it To the Professionals
If can budget for it, you may want instead to opt for a wedding at a hall or other outside location. You can cut costs by having the food served banquet-style or by having the party late enough in the evening that it has an hors d'ouvres and dessert menu rather than a full dinner. Have music available if you'd like, and decorate the hall in your wedding colors.
Should You Ask for Gifts?
You should not ask for gifts at a post-wedding party. It is bad wedding etiquette to ask for gifts from anyone who wasn't invited to the wedding ceremony. You may want to add a small note to your guests' invitations indicating that it is not necessary to bring a gift, or if your gathering is on the smaller side, let a few friends and family members know and have them pass the word.
Last of all, be sure to send thank-you notes to those who shared in your special day. Unless you require a definite head count, keep it on the casual side and make sure your guests are comfortable and feel welcomed. With these tips, your post-wedding party will be a day to remember.