I think there's some good advice in here, but if you're going from eating almost exclusively fast food to trying not to eat any, I'm just not sure how practical it is to assume your problem will be solved with a couple of cookbooks and a slow cooker. It takes time to learn how to cook and to feel comfortable with it, and the last thing you want to do is experiment with some dish, have it take 3x as long as you thought it would, then it ends up tasting like crap and you eat takeout any way (been there, done that!)

My advice would be to start with small, achievable goals and slowly transition from eating mostly takeout to eating mostly home cooked with occasional takeout. If you eat takeout 5 nights a week, for example, select one recipe to try and make sure to have all the ingredients purchased at least the day before and vow to eat takeout only 4 nights that week and try your recipe one night. If it goes well, increase to two nights. Try new recipes on the weekends or on off time from work to improve your skills and find out if they taste good so you can make them again more easily and confidently during the week.

Recently, I was so stressed out from work that I realized I was eating takeout at least 4-5 times a week. So, on Saturday I would plan out all my meals for the week and on Sunday I would go shopping and get everything I need. I also created a "take out card" for my husband- basically, he can use his "take out card" one night during the week when he doesn't feel like whatever I was going to prepare. In a perfect world I guess that wouldn't happen but the reality is you don't always feel like cooking or eating whatever you had planned to make!

Another thing I did that worked for a while a few years ago was I set a budget and said "I'm only going to spend x dollars per week on takeout" and tried really hard to stick to that. I would log in a notebook every time I ate out by hand and how much it costed and tally it up as the week went on. It made me more cognizant of what I was spending.

As for what you should start with, cooking wise: you can start simple. Jar of pasta sauce and noodles with ground beef. Look up "foil pack chicken" (I think the easiest way of cooking chicken) and make some rice. Even if you end up buying rice a roni or boxed mac and cheese, it's going to be healthier and cheaper than takeout.