The difficulty of sewing on letterman jacket patches depends on the material of the jacket leather or fabric. It's easier to sew a letterman jacket patch on a fabric jacket, because fabrics are more forgiving to mistakes. Also, make sure you use the same color thread as the color around the patch so the stitches don’t show. This tends to hide mistakes better.
Start by threading the needle and pull the thread ends together until even. Then knot them together to form an anchor to the fabric when sewing.
Once you have your needle threaded, you’ll need to position the patch onto the jacket. If the patch’s edges are bit curled, you may want to use an iron on it to flatten them out, also some patches now have an iron-on backing so it will help increase the bonding of the patch to the jacket.
The patch must be secured to the jacket in order to avoid wave or bubbles under the patch as it is worn. Once it’s attached, make sure to place pins all around and one or two through the patches middle to secure it as much as possible before you start sewing.
With the patch attached to the jacket, temporarily, it’s time to take the threaded needle and start sewing. Begin from the inside of the jacket and work outward. Pull the threaded needle out over and around the patch’s edge before pushing the needle through the fabric and out the back.
Continue to sew around the edge of the patch spacing your stitches no farther than one-quarter inch apart. When you’re done sewing around the patch, make sure to anchor the thread on the inside of the jacket to finish.
Leather is less forgiving of mistakes than fabric so it takes a bit more time and patience to attach a letterman jacket patch. If you must sew it, it’s best to have a professional do it because it involves removing the lining of the jacket and it take a higher level of sewing experience.
If money is an issue you can do it yourself by using an adhesive that is made for leather. To do this, make sure you have the patch exactly where you want it by taking some double-sided tape and attaching the patch to the place, you want it. Once you’re sure this is the right place then remove the tape and follow the directions on the adhesive can.