With all of the new computer software allowing printed versions of a stained glass template we seem to forget about basics. The best technique still today is to create a full size draft of the panel to be made and when doing so create a "pattern" or template copy.
Print out tiled patterns as you would straight from your computer then transfer the pattern to a heavy weight working copy. Then transfer that copy to another pattern copy that will be used to create the actual template or pattern pieces.
Once you have the two copies you are ready to cut up the pattern copy with pattern shears. This may seem a bit of work but in the end will make a lot of sense and will guarantee a good fit.
A good type of paper to use that remains rigid but is easy to cut with pattern shears is #70 lb. kraft.
Large size graphite paper will be needed for pattern transfers and is available at most drafting and craft supply stores.