During my trip to Office Depot with Stacey, I was told about shipping labels. Why I didn't think of this, I have no idea.
On my trip home for Christmas, I had my mom help me with all of the addresses. I am really not good at keeping up with everyone's address unless I specifically ask for it. So, with that said, she helped a lot. I got the larger labels that were clear. This gives you the opportunity to set different fonts and make sure there aren't any mess ups. Not to mention, it really saves you time and frustration.
I purchased the 2" x 4" labels. A package of 100 was $10.99. It comes with really detailed instructions and a website you can go to in order to download the correct template.
Once your template is downloaded, you type your address, print them off and stick them onto the envelopes.