If you're anything like me, you do not want to spend money purchasing a lettermate. I've been wanting one, but really it's $10 for something you might use once to address your wedding invite envelopes and then sits in your drawer.
I'm working on addressing envelopes for our Christmas cards, and figured out a free alternative to purchasing the lettermate! I took a regular sized index card, folded it in half, and cut 4 lines leaving two space between each line. I had to trim it a bit, but I then took the index card and used a pencil to draw light, evenly spaced lines. Once I've written the address, I use my good eraser to erase the pencil markings. Now I can write my addresses without going crooked or buying a $10 lettermate.
Maybe I'm an idiot and everyone knows this, but I thought I would share the tip that I just discovered! Let me know if you have any cool advice on writing addresses on envelopes
Here's the lettermate:
http://www.thelettermate.com/shop/the-lettermate