Lovely to hear from you.
As a mandatory, we need both your names, obviously ;) ! The date and time of the ceremony and where it is, as well as the location address. Then what is happening with the reception, ie 'reception to follow'. Then how you'd like your guests to rsvp and by when, if you are trying to cut information this can just be done by redirecting them to a web address where they can reply. But most of my clients put the rsvp date and either an address / email or mobile on the invite if they aren't doing an rsvp card. It just makes things as clear and easy as possible. Dress code is optional, some of my clents are leaving it off - hopefully noone would wear jeans! I hope this helps somewhat, here are some sample wordings if they are useful - there is no right or wrong, people often use their own expression. Let me know if you need anymore advice :) Claire.