Etiquette tips for the mother of the bride include not setting her own expectations for the wedding, offering realistic help to the couple and not drawing too much attention to herself. She shouldn't invite people to the wedding until the guest list is complete.
Regardless of who pays for the wedding, the day belongs to the couple. The mother of the bride should support them and understand that they ultimately make the decisions. Supporting them helps minimize their stress.
She should tell the couple ways she can help, and tell them to let her know what they need. The couple is more likely to ask for help when she offers it, instead of trying to take over certain aspects of the wedding. If she has an idea for the wedding, such as a family tradition she'd like included, she should present it and let the couple decide.
She should avoid actions that place attention on herself instead of the couple, such as showing up late, wearing a white dress or drinking too much and making a scene.
The amount of guests that can be accommodated varies depending on the venue. The mother of the bride should refrain from telling people about the wedding until the couple completes their guest list and knows who they can invite.