I know I cover this topic a lot, but it comes up a lot.
Here goes:

• The words honour and favour are traditionally used when the ceremony is being held in a house of worship or for a formal invitation.
• While traditional invitations use the phrase “at the marriage of” it’s fine to alter the words for a less formal invitation. For example, “invite you to the wedding of…” or “we hope you will join us for the marriage of…”
• There is no punctuation except for the periods after Mrs., Mr., etc. and where phrases requiring commas appear in one line (Saturday, the seventh of June).
• Titles such as “Doctor” and other professional titles/military ranks are written in full.
• Names are written in full. For example, if the groom goes by A.J., his name would be written out as Adam Joseph.
• When an invitation is to the ceremony only, it does not include an rsvp.
• Numbers of the street address (on the invitation – not the envelope!) are written as numerals: “519 South Eads Street” but when there’s just one number it’s spelled out: “Ten East Avenue”
• Half hours are written as “half after five o’clock”, not “half past seven” or “seven-thirty.”
• Numbers of the date are spelled out: “the ninth of August”