You don't have to be able to make a suit from scratch, but some basic skills will save you big. If you find a great skirt but it's too long, it's nice to know how to shorten it. It's also useful to know how to sew on a button and repair torn clothing. And a few simple home projects can easily be completed in an hour, such as a blanket, pillow, table cloth or draft dodger. It's also rewarding to have a productive hobby that could potentially save you money instead of costing you money. Homemade gift possibilities abound, too, when you own a sewing machine and know just a few things about sewing.
You can get started here. Another possibility is to check out your local library, high school or community college. Often they have classes for adults that meet for just an evening or a few weeks. You'll find that these classes will pay for themselves, especially if you find a sewing maching on Craigslist and begin doing your own clothing repairs.