I recently had a very nice lady help me with my sewing machine and giving me some parts for it. she gave me some scrap Fabric and I learned how to make a boy's vest using a pattern she gave me. I'm really excited by what else I might make. Jo anns usually has a small basket of scrap fabrics. I could use that to practice some more stitches. I would just hate to mess up or waste more expense fabric.
Learning to sew using scraps of fabric is a great way to practice without having to worry that you'll mess up some more expensive fabric. I'll use old socks to practice sewing on too sometimes, especially if they're already ripped and unusable for anything else (and my dogs are done destroying them!)
Walmart often has some great deals on fabric, as well. I've purchased some small sewing items and button on eBay. My sewing machine isn't working right now, and I haven't taken the time to mess with it, but I'm sure eventually I'll get it back in working order. For now, I just make simple repairs by hand. I've also seen patterns on sale on eBay at reasonable prices, but you might also be able to find some for free on Pinterest or other craft-related sites.
My mom taught me how to sew and I can do basics. I remember having to cut out the patterns that she would buy. She made a lot of our clothes when we were small and made all of our quilts. My mother was very crafty and did this sort of thing all the time. I wish I was better at sewing, but I do not have a sewing machine to use anyway. I remember sewing by hand and how hard it was to sew the quilt blocks together. It definitely gives you a new appreciation for handmade items.
Go to the thrift store and purchase an old men's shirt and have fun practicing. I go to the thrift store all the time and pick up old shirts or dress to make into items I want around the house, sometimes just for rags.
You could get some cheap fabrics at a thrift store, then you could have enough fabric that you could play around with to get some meaningful practice. Purchase enough yardage to give you the freedom to literally lay out a complete piece of the garment instead of scraps which might give a bit of problem because you would probably have to be joining pieces to get the whole.
I always wanted to know how to sew when I was younger, I loved watching my grandma sewing and begged her to teach me. She said if I still wanted to learn when I grew older she would teach me. But it never ended up happening. I guess we get busy when we grow up and have new priorities and responsibilities! I still would love to learn, but I know it would take a very long time to actually start creating my own clothes. I'm not sure i could afford to spend all that time now, specially because I really don't see myself being good at it!