I found that just reading up on every diet out there and finding one that is pretty close to what you eat anyway was the easiest for me to lose a ton of weight and what worked for my friends.
Read up on each of them. Vegan, Keto, Adkins, Paleo, weight watchers, liquid juicing, whatever. If you happen to like the foods in one of them, give it a shot. Most of them work just fine, it's just can you keep it up? It's really about what you can maintain. It's easy to lose weight if you just stick to something that works. There's nothing worse than trying some diet, then hating it and ending up with more weight than you started. Starving is just bad no matter what. That's a path better not taken.
I ended up going with the Slow Carb diet that Tim Ferris came up with. It's basically just cutting carbs and dairy out. I didn't really like most dairy anyway and carbs, despite my love of rice wasn't too hard. Ditching the bun on everything and giving up potatoes wasn't a big deal to me. Pretty much limited to water, coffee, and tea for drinks. It's very close to the Ketosis one, but not quite as extreme. Keto demands you stick to it completely and you can't cheat or it's devastating to your waist, heads up on that one. Slow carb lets you have <not allowed> every so often including pizza and beer. I like that. I've lost 76 pounds from it (50 to go!) so I know it works, but that's what worked for me. Find what works for you.
Then there's exercise. Not as effective as some people like to think, but it's far from a bad idea. Think of it like this. Generally speaking running burns about 100 calories per mile. That's a really rough number, but close. So to burn off a mcdonalds quarter pounder, you'd need to run around 4 miles. eek. That's not even counting fries and not walking or jogging, that's running it and breaking even.
It's still great for the heart though. Cardio is aptly named, good for the heart. Muscle training is best for losing weight I found. More muscle means faster burning even when sitting still. Not to mention, women in shape tend to be pretty hot. So there's that. So do what you can handle and go with that. It's never a bad idea just don't think you can work out 5 days a week and burn off pizza service all of the time. There's a reason everyone says diet AND exercise is best.
And what Rakel said is spot on. Smoking is contraindicated. I had to give that up too. Alcohol is serious calories. If you can't stop, at least bother to look up what the calorie content is, you might have second thoughts about that drink after seeing it. Liquor is just flat fattening. Beer is carb heavy, but some aren't too bad. Light beers like Amstel light are the lightest on the waist. I go for Guinness Draught. easiest one I found to enjoy and still lose.
