There are several ways to "use" your vintage patterns while protecting them from degradation. The first way to save and use a pattern is a technique I reserve for patterns than have been severely used, abused, or neglected and will never again be considered of collectible quality. This process is also particularly useful if you are planing on using the pattern multiple times.
Begin by pressing your pattern tissue with your iron set to a low heat no steam setting (if you haven't learned this the hard way already, steam will shrink your pattern tissue). When the creases and crinkles are gone, set each piece aside on a flat surface until all your pieces are pressed. Then using the thinnest fusible interfacing you can find, adhere your pattern pieces to the interfacing. I prefer Pellon Quilters 1" Grid because using the grid allows me to resize a pattern as needed (something to talk about another day).
To do this simply lay your interfacing out on your ironing surface fusible side up. Adhere your pattern pieces right side up by aligning the straight of grain marker with one of the grid lines. Tack the pattern in place by using the tip of your heated iron (set to heat appropriate for the fusible interfacing) on the corners for a few seconds being careful not to allow iron plate to come into direct contact with the interfacing. When the pattern is tacked trim the interfacing to the edge of the pattern piece. To complete the fusing process press the pattern one section at a time. DO NOT slide the iron around on the pattern as this will cause it to wrinkle.
Another way to use your vintage patterns - those of a collectible quality - while preserving their integrity, is copying. To copy you can use most any kind of paper, butcher paper (which can come on very wide rolls), parchment paper, blank pattern paper (can be quite expensive), wrapping tissue or even regular old bond paper put together with a little tape. Use what you have on hand - don't spend a fortune if you are only going to use the pattern once. If you plan on using the pattern multiple times or will need to make alterations for fit then buy the best - pattern tracing material. This material is a very durable, non woven, semi transparent fabric that can be sewn together for fitting and altered by placing marks on the material. 
Want to give pattern tracing material try? Check out my shop listings for 5 yard increments and by the yard special orders http://www.etsy.com/shop/PiePoe
