Please put the day of the week on the invitation. (eg, "come to my party on Sun. 6 March", not just "come to my party on 6 March". (It's only 3 more letters.)
So many invitations seem to omit the day of the week, and I don't think I can be the only one who has to keep checking against my calendar to work out whether a party is on Saturday or Sunday. I also know that I'm not the only one who has ever taken a child to a party, only to find that we've arrived on the wrong day
.