1. Start with a jacket you already have. You could do a military, denim, adirondack, tweed, blazer... Anything.
2. Then go to a thrift store and find an old sweater or t-shirt with a print you like that compliments the color of the jacket. Tribal or floral always looks great!
3. Then cut a larger piece than you actually need for each cuff and for the collar.
4. Put fabric glue onto the jacket where you want the fabric placed. Then place the fabric onto the jacket. Make sure it's all nice and adhered on and then flip it over and cut off the excess fabric. No sewing, no pattern needed.
TIP: You can always peel it back and add more glue if needed or go over it with a sewing machine, if you have one.
Also, remember how often do you wash your blazers?