It is important to take other people’s feelings into consideration to avoid friction with your family and your future in-laws.
1. Decide on the guest count, and divide the total in half so that both sides of the family have the same number of guests to invite. You can then divide those 2 groups in half so the parents have their own count apart from yours, or you can work together to fill those seats. Establishing a count ahead of time will save you the aggravation of having to cut too many people
2. Establish hierarchy when choosing guests for your wedding. Obviously, immediate family members come first, followed by close friends, and finally acquaintances. If there are situations in which a friend has been a part of your life more than a family member, then that needs to be taken into consideration.
3.Create a set of rules for selecting wedding guests and make sure you, your spouse-to-be, and each set of parents understands that they need to abide by them honestly. For example, you can ask that only those who are currently associated to the 4 family members be invited, and not long lost friends.
4. Determine whether children are invited. Where some people prefer that children not be invited for fear that they will be loud during the ceremony or cause havoc at the reception, others feel that a wedding is a family event and children are part of the family. Another option is to have children only attend the reception. Understand that some guests many choose not to come if their children are not invited.
5. Assume that approximately 20 percent of your invited guests will not be able to attend. For this reason, you should create a backup list of guests that you can invite. Again, this list should be in order of priority, and you may have to choose guests from the same pool of invites. For example, if a guest from the bride’s parent list declines, then another one of their guests should be invited.
6. Establish a date when the backup guests will be invited. You don’t want to send out last minute invites. This second round of invites should have its own RSVP date.
7. Remain in control of the wedding guest count by accounting for guests’ guests. When sending out your invites, write “wedding guests” on the envelope if the person you are inviting is allowed to bring a date. If you leave this off, it is understood that the individual is expected to attend alone
Source: Wiki How