Switch to water. Force yourself to like it. Trust me, it's more than worth it.
I'm being realistic here. Is water healthier? Yeah, but they both have 0 calories and sometimes you need the taste.
Eating at home is always preferable. If you know how many calories/fat something has when you eat it, all the better. Try to figure out how many calories are in each meal you have, just knowing will steer you towards better choices. Purposeful ignorance can be dangerous.
I always say that there's good news and bad news when trying to be healthier. The bad news is that it's not easy: there's no magic system that lets you not have to eat healthier or not exercise.
However, the good news is that it's not as hard as you think. People make the mistake of "going on a diet", which is WRONG for any sort of health improvement. Simply put, "going on a diet" implies that you will "go off" it at some point, and resume your prior habits. All that means is you will lose any progress you made, and you will not be happy.
Be smart about your limitations. No one expects you to eat salad three meals a day for the rest of your life, so don't even try. The more difficult changes you make, the more likely you will throw them all away when you mess up.
Make several smaller, but permanent, changes. There will be times where you will want to eat pizza or fast food, and it's just ridiculous to say you will never eat out again. It's okay to go, but try only going in a group, or when you can't get home to make something yourself. In short, don't go out by yourself to eat crap.
Go to the grocery store and look for things you like, or might like. If you don't like to cook, find stuff to microwave, or just get sandwich ingredients. Don't worry too much about getting health foods, but do look at the calorie counts and serving sizes to get an idea of what you're intaking at each meal. Again, you don't have to always go for the least calories, but you'll probably be turned off when something has a very high count.
Don't buy snack foods, resist the temptation. It's too easy to open a bag of chips and end up eating the whole thing in a day. Just take them out of the equation completely. You can always get a small bag of chips at Subway or something. If you have to munch on something, find some non-sugary cereal, or better yet, vegetables.
When you get home, try and see what you like. Whatever you enjoyed, stock up on that. Make a habit of preparing these home meals instead of going out. The key is making new habits that stick. When you think to yourself "time for dinner, I think I'll cook this", you're doing better. Routines are hard to break, so you have to prepare to make it as tolerable as possible.
If the changes seem torturous, you're doing something wrong. I'm not saying it will be easy, but things do not need to be constantly unpleasant. Remind yourself of your motivation, and keep in mind that every little change adds up over time. If you eat something bad, don't feel like you lost, just make yourself that much more motivated to do better next time. Don't give up.
Get a scale if you don't have one, and keep a weekly journal of your weight. Try to weigh yourself at the same time of day each week, and resist the temptation to check every day. It's very important to keep track of your progress, so you can see if things are working or if you're slipping. Don't let your mistakes surprise you weeks or months later. If you check every week, you will have plenty of time to react before you lose too much progress.
Okay, I wrote a lot. I was actually planning on making this topic myself one day, but never got around to it. I'll write about exercise later, but let me know if you have any questions on what I wrote so far.
