I would highly recommend coupling diet and exercise. Just doing one won't be enough.. but if you already eat relatively healthy, here's some beginner tips. (I train my mother, who's got a disease and she's pretty newbish when it comes to exercise.)
- Warm up and cool down. Nothing fancy, take about 5-10 minutes for each. For a warm up you want to do some simple moves to get your heart rate up and get your body and muscles warm.
http://www.usfsa.org/content/Exercises.pdf These are really awesome, just pick a couple you like.
- Cardio for about 20 minutes. This will burn off your quick energy, making everything you do afterwards pure fat-burn and muscle-gain. Walking on the treadmill, swimming, jogging, playing a sport, anything you want. If you walk, aim for about a 15-17 minute mile pace (or, if you don't know what that feels like, walk and sing along with a song.. if you have trouble singing and don't really feel like it then you're good. If you absolutely cannot talk, you're working more than you really need to for this segment. It should be uncomfortable, but not killing you.)
- Switch off and try new things. Lifting weights really should be your focus to begin with, because building muscle means burning fat.. so just do a circuit. Usually they line all the leg machines, ab machines, and arm machines up in a row. Switch it off--do arms and back one day, legs the next day, and maybe a longer cardio session the third day. Just jump on the machines, push the weight around for 3 reps of 8-12 and then jump on the next machine. Don't worry about how much weight you can do... just adjust it until you can do at least 8-12 reps. You should have a lot of difficulty completing those reps, but not enough that you cannot do three sets of them. It should not feel easy, but you shouldn't feel like you're dying on them.
- Work on your abs every day. Spend the last few moments of your work out working on crunches and left lifts and things like that. Your abs can handle daily work outs and it really is necessary to keep your core up with the rest of your body. Those muscles are deep and layered so making sure you get to them all means every time you work out you need to focus on them a little.
- Cool downs should be stretching. Warm ups should not be straight-out stretching because it really isn't good for your muscles, but stretching is the best way to prevent lactic acid burning in your muscles, injuries, sprains, and aches.
Also, obligatory disclaimer that water is important here. I don't know what kind of gym you have, but if you have one with a pool I highly recommend swimming. It is fun, and it is the best workout there is. If you have classes you can attend, you might want to get into those because the instructors will try to hold you at least somewhat accountable for coming back. Even if you feel silly during it, it is still a guided work out by a professional. If it is just weights, feel free to ask others what they do people are usually MORE than happy to tell you how to work out Lol..
As far as eating habits. I just discovered this "salad in a mason jar" thing and it really is saving my vegetable crisper. Pastas you can never go wrong with. skinnytaste.com has a lot of really awesome recipes for substitution-based cooking and eating. I know you like to experiment so maybe just find some tasty go-to meals and stick with them for a while?
Don't know what everyone else wrote, but good luck with it all.