Content: Most important in all, make sure to consult with both families involved here. Usually I would recommend that the couple leave this out to the bride's parents to complete. You see parents take pride in this act. So tell the bride's parent to provide a drafts of what they want the content to be. You can then verify the appropriate names with the groom's parents.
Once you have feedbacks from both set of parents you can add your own input. This way all the church, reception, RSVPs information would be correct.
Fold: You can have your wedding invitation to fold horizontally or vertically. Just like in a greeting card this will determine what how it is opened once taken out of the envelop.Seal: Add a personalized touch by using a seal on the envelops!