First things first: you need to get all of your guest addressing information into a spreadsheet or database. I used Microsoft Excel, and created data columns for Guest Name, Street Address, City, State, and Zip Code. You can break it down however you want, but this was the easiest format for me to deal with.
Before you even open Word and start merging, you need to decide which labels you want to use. There are so many different sizes, and if you're using Avery labels, MS Word comes with templates. You just pick the template number associated with the labels you're using, and you're in business--someone has already done the hard part. In my case, we're using two label types (both are clear labels): for the invitees' addresses we're using Avery template 5164 (3.33" x 4"), and for our return address on the back of the envelope, we're using Avery template 5160 (1" x 2.63"). Labels come in all shapes and sizes, and even if you choose to use off-brand labels, the Avery template number is usually printed on the box somewhere.
So, you've chosen a label type. Excellent. Open MS Word. Go to your "Mailings" tab and click on "Start Mail Merge." Select Labels.
Pick a template, any template. No--pick the one you need. (make sure to double check the label information on the right to see that it's correct).
