You can trace, and make the trace as clean as possible, then use a copier or a place that has copier service to enlarge.
You can enlarge in increments, or tiles if the image is larger than the paper. You tape the pieces of paper together and retrace to cut out.
You can also enlarge by graph paper. You'd have to search for the technique. I'm lucky enough to have an Illustration program and can trace on the computer and print at desired size even by tiling.
If you wish to learn to do it digitally, there is a free open source program called Inkscape and forums for its use. It runs on Windows and Linux, probably Apple, too.
Here's a forum:
http://www.inkscapeforum.com/viewforum.php?f=5