Someone asked me if I still use guide sheets and I proudly responded "YES!". I don't think there is any shame in using guide sheets. Sure, after time, you will have the muscle memory to be able to write letters with a somewhat consistent x-height & slant, but when it comes to client projects, I like using guide sheets with clear x-heights, baseline, centered line, and slant lines to ensure that my lines are clean and my work looks professional.
I recently finished an envelope addressing job for a wedding and after making mistakes and experimenting with different x-heights and baseline spacing, I decided to make my own envelope guide sheet on Illustrator.
I may tweak this for different envelope sizes because smaller envelopes will require a smaller x-height, but this guide sheet works well for a 5.5x7.5 envelope! Place the guide sheet on top of your lightbox and then align your envelope on top so that it is centered. Click on "Envelope Guidesheet" to download!
X-height: 3/16 inch
Baseline spacing: 5/8 inch
*Please note that this is copyrighted and for personal use only. Thank you!*