The best piece of financial advice I have learned was to learn how to cook and cook most or all of my weekly meals. During college and after graduating, I had absolutely no skills in the kitchen and wound up eating mostly take-out or sit-down dinning for my meals every day. Not only did this cause me to gain weight because all I would ever order were burgers and pizza, but I was spending hundreds of dollars a week on food.
A few months out of college I realized that I couldn't afford my current lifestyle of eating out after paying for my rent, student loans, and other miscellaneous expenses. On average, I was spending $20 - $25 a day on lunch and dinner on the weekdays, and sometimes around $50 a day on weekends. One day I realized I couldn't go on any longer living like this, so I hit the grocery store, loaded up on a variety of foods, and forced myself to learn how to cook. I started slow, making a few dinners a week and packed lunch everyday. After a few weeks, I purchased a slow cooker, and began making large meals on Sundays to prepare for the whole week ahead, so that I could just come home and reheat some food if I was too tired or not in the mood to fully cook a meal. Some people find it daunting to cook for only one person, but I have found it easier to cook double the amount and keep leftovers for another day.
Over the past 3 years, I have continued to bring a healthy lunch to work everyday, and have continued to cook myself dinners 5-6 times a week. I try to go out to a nice meal once a week or so, and going so few times a week makes me enjoy the experience much more. My weekly trips to the grocery store cost me around $50-$60, as opposed to the $200 or so I was spending a week on take-out. Today, thanks to my work in the kitchen, I have lost weight on my body and gained weight in my bank account. This piece of advice has taught me to save thousands of dollars over the past few years, and will help me save much more in the future.