Your save-the-date can take any size or form. If you decide on mailing cards out, then your cards can be the size of a postcard, or even smaller. Make sure the size does not cramp the wordings together.
Stop to think for a moment: You have painstakingly put together your wedding event, and done all you could to make this as perfect as you wished; but you take a look around your guests and realized that only half of them were able to make it to your wedding. You obviously missed out your wedding save-the-date cards to ensure your guests kept themselves available on this special day of yours.
Rules & Etiquette – Again, few rules apply. The only information you must include is your names and wedding date, although I suggest including location information as well so wedding guests can begin their travel plans. Aim to send save-the-date cards soon after you secure your date and venue, or about 4-6 months prior to your wedding. Remember, everyone who receives a save-the-date also receives an invitation, so have your guest list finalized prior to sending them. You can, however, always add guests later (there is no rule that says everyone must receive a save-the-date card). Although formal replies are not required, you can get preliminary attendance estimates through word-of-mouth.
Some companies offer digital save the date cards as well. What this means is you have the card to use on your computer and you could send them out to any email address that you have. Since almost every household has a computer and an email address, this would be a good way to save money on postage stamps.
If you are creative and want to save money, you can create your own save the date cards using either card stock paper or regular paper. This will save you money since you will be printing them yourself. You can be real creative when you design these. You can include a picture on the paper and include any other personal details you would like.