If you like to sew with vintage patterns, you know they can be quite fragile in their original state. Or maybe the pattern you have in mind is not quite the right size and you need to grade it up or down and need it in a form that you can cut up. I thought I'd show you the method I use for tracing my vintage patterns. This tutorial shows was done with an unprinted pattern, but I've added comments when needed to adjust for those with printing (rather than perforations of unprinted).
You will need a few supplies: paper (you can use inexpensive banner paper from the office supply store, exam table paper, blank newsprint, or Swedish interfacing), ruler and/or yardstick, pencil, fine tip marker, paper scissors, pattern weights (I use large metal washers from the hardware store), pins (for printed patterns only), and a flat surface (in this case, a cutting mat).
Begin by ironing all the pieces on the lowest heat setting for your iron, without steam. If in doubt, test on a piece of paper first to make sure your iron won't scorch the paper. You need to iron out any wrinkles or deep folds in the pattern pieces so they'll lie flat. Just be careful not to tear the pieces.
Lay the paper on a flat surface. Arrange the pattern pieces on top with pattern weights atop to help straighten the pattern and keep it flat. If the piece has a straight edge (such as the one pictured with the center-front edge to be placed on folded fabric), you can lay that alongside the straight edge of the paper to reduce one more edge to trace.
Begin tracing around the edges of the pattern with the pencil. I tend to sketch around curves and uneven edges, and make dash marks every 8"-12" along straight edges that I can fill in with a ruler after the pattern is removed.
Be sure to mark all the circles, notches and diamonds! When transferring a dart marking, I indicate those with small dots and connect them later with a ruler for a complete dart shape. If you're tracing a printed pattern, I tend to pierce through the pattern and paper beneath with a pin to indicate a pattern marking. After the pattern is removed, I go back and add the mark with the pencil or marker.
Remove the pattern piece and fill in any spots with the ruler/yardstick. I also indicate all darts and grainlines at this point too.
Finally fill in the pattern information: company, number, size, piece and quantity to be cut with marker (if this is a final piece; if you're using it to grade the pattern, you don't need all the information). I also like to include notes on seam allowances, darts, hem depth, etc. on the pattern piece. Now you can cut the pattern out and start on the important thing: sewing!