Tips for Sewing Denim. Denim is a very strong, long-lasting fabric that has been extremely popular for over 100 years. If you need to tailor your denim or have a tear, you must arm yourself with high quality thread and very sharp, strong needles. Average thread and needles will not work with this tough fabric. If you are sewing your own jeans from scrap, make sure you have the proper tools for the job.