I recently spoke with a follower who said she doesn't know how to cut and score a handmade card. She lives in a very remote area, and has not had anyone to teach her.
Since this is one of the most basic skills a new cardmaker needs to know, I thought I'd share the answer here. Chances are that there are others out there that don't know the basics, but haven't spoken up.
Let's start with the paper cutter itself. Here's a photo of the Stampin' Trimmer comparing its ruler to a regular ruler. You can see that the numbers on the metal ruler read from left to right, and those on the Trimmer read right to left. Click on any of these photos to see a larger view.
That means when you are going to measure a cut on a paper cutter, you place the part of the card stock you want to keep so that the left edge is on the measurement line for the size you want to cut. If you want more help on measuring fractions on your paper cutter, you can watch this video on YouTube: How to Measure 16ths of an Inch. It will go over all the fractions on a paper cutter, not just 16ths.
The most common size for handmade cards is 4-1/4" x 5-1/2. One reason for this is that it is exactly half of an 8-1/2" x 11" piece of card stock. This is what it looks like when you position a full sheet of card stock on the Trimmer to cut it in half. The 11" length is along the top of the Trimmer and the left edge is at 5-1/2".
Now you can run the cutting blade down the groove of the cutting guide, and you'll get a perfect cut for two card bases. Each piece now measures 5-1/2" x 8-1/2". If you fold one in half, you'll get a 4-1/4" x 5-1/2" card. Easy peasy.
I like to score the card stock before folding it, because that tends to give a cleaner fold. The Stampin' Trimmer (and similar paper cutters) come with both a cutting and a scoring blade. Here's a picture of the card stock positioned for scoring.
You can see the cutting blade (dark gray) is moved out of the way so I can use the light gray scoring blade. The 8-1/2" length is along the top of the Trimmer, and the left edge is at 4-1/4".
Once you've scored the card stock, you can easily fold it in half, then crease the fold with a Bone Folder to get a professional-looking card base.
If you've already been making cards, this may be very automatic for you. But I find that many people who've been stamping for a long time still have trouble measuring fractions. If you're one of those, and are tired of getting imprecise cuts, watch the YouTube video on How to measure 16ths of an Inch.
If you're new to cardmaking and paper crafting, this post should help you learn how to cut and score a handmade card.