An Ongoing List of Recommended Things

• How to Darn A Sock
  Tutorial: Youtube
  Notes: This is the method I use. It's an older video but I find it easy to follow along with. If the hole isn't visible when wearing shoes, using larger yarns/embroidery thread makes the darning go faster.
  Pro Tip: Pick up yarns/embroidery threads at thrift stores and charity shops. There's no need to pay top dollar for repair materials.
• How to Sew a Button
  Tutorial: Youtube
  Notes: Give yourself the extra room he recommends. Buttons that are looser have less likelihood of wearing off too quickly. Too loose, however, and it'll snag. A paperclip, extra needle, or a few pins will give you enough room.
  Pro Tip: Often shirts have a tag in the inner seams with an extra button attached for when one inevitably springs loose.
• Thrift Stores: Before shopping elsewhere, try the thrift store.
• If you want to sew but can't afford pricey fabric, thrift stores often have sheet sets that are missing pieces, which give you large amounts of matching fabric.
• Old blankets can be used as quilt batting.
• Shirts with missing buttons can be fixed with the tutorial above. 
• Jumpers/Sweaters with good yarn can be unravelled for large amounts of yarn that are all the same weight and dye lot, even if they have holes. See below.
• Felted knits can be cut into mittens/socks.
• Learning how to do basic tailoring skills can allow one to buy a size up and tailor to shape.
• Please don't buy plus-sized clothing if you don't need it. Many plus-sized people need clothing and it's often at extra cost in stores, so leave plus-sized clothing to those who would like a nice new outfit.
• Unravelling Knits:
  Tutorial: Photo Tutorial
  Notes: Look for larger sizes of yarns, and no felting. Felted knits won't come loose. (If you don't know how to find felting, look at the stitch definition. If you can see each stitch clearly, it's probably not felted. Also, felting only happens with wools, so check the tag!)
  Pro Tip: Serged woolens aren't any good for unravelling, but they're great to felt in the washer/dryer and cut into mittens or hats!