I posted a couple of months ago regarding envelope addressing and wanted to share my *NEW* "Small Envelope Addressing Template" for your personal use! Baseline spacing is tighter at 0.5 inch apart and the x-height is at 0.17 inch. This guidesheet works well for smaller envelopes such as your RSVP envelopes. Click below to download both versions (the previous one is also updated! I included 'x' marks to indicate x-height and also included a landscape version for those mega envelopes):
HOW TO USE THEM
You can use these guide sheets for both light and dark envelopes. They contain the 55 degree slant lines, x-height, a center line, and enough spacing between the baselines for you to add flourishes! You simply place your envelope on top of the guidesheet and use the center line as your reference point to keep your lines centered. If you are aligning every line to the left, you may want to draw in more vertical lines that's more personalized to your needs.
Here is a quick process of how I address light and dark envelopes...
For white/cream envelopes, it's best to use a lightpad! I use the Treviewer Super Thin LED Tracing Lightpad and it's been such a lifesaver! I've also heard great things about the Artograph Lightbox. I place my envelope & guidesheet on top of my lightpad and start writing. There's no drawing lines/erasing. Having a lightpad has saved me so much time. I like the one I have because it can lay almost flat, but you can also angle it. The light is adjustable so you set the brightness to how you like it. Not only do I use it for envelope addressing, but for writing placecards, letters, and designing prints.. I really can't recommend getting a lightpad enough!
For colored envelopes, you won't be able to see the guidesheet with a lightpad, so I use a laser level! I've seen people use Slider Writer ($59.99), but I'm been pretty content with my Black & Decker Laser Level from Amazon (only $15!). I got it 2 years ago and it's been working great! I love that it's portable and I think I only replaced the batteries 2 times. How do you use the laser? You first place the envelope on top of the guidesheet, center it, and then line up the laser to the baseline. I mainly use the laser to make sure I'm writing in a straight line. The guidesheet will help you estimate the x-height and ascender line as you write.
Hope this helps!