Let me preface this by saying that I'm not a trainer, but I've trained in just about every way imaginable. Right now I'm with this guy
http://www.pb-training.com/ who is a friend of mine, and I've learned more in the last year than I've learned in the last decade. He trained the Olympic Skeleton team, and although he's demanding he gets results. A few things that he's big on:
Hydration. Water intake and proper hydration is HUGE, but slamming back 5 glasses of water all at once isn't going to do much, because your body can't absorb it that quickly. Try spreading it out over the day.....I usually put back about 8 litres over 12 hours. Yes, it's excessive but I find that when I'm hungry or need a diet coke fix (which I've managed to stop drinking) I tend to reach for the water bottle. Getting up and walking to the water cooler also gives me an excuse to leave my desk when my eyes are burning from staring at CP all day. I also dehydrate myself quite a bit....I run up to 4 days a week, weight train 2 or 3, hockey 2 days a week, and try to get into K-country biking once or twice. If I don't drink enough water I feel hung over every morning.
Sleep. If you're not getting enough sleep you can't mentally focus on your training, and you start getting pretty lazy with workouts. If you lose intensity you're not going to get very good gains. I'm supposed to be writing down my heart rate first thing in the morning and throughout the day, which apparently tells you if you're sleeping properly. I don't do it though.....I'm not training for the friggin olympics so I "forget" to do it every morning.
Diet. Like Soulchoice said, it's at least 70% of your weight loss goal. Going for a 30 minute run isn't going to compensate for a dozen beers and the hamburger people scarf down afterwards. I also avoid red meat and a lot of dairy products, because your body has a hard time digesting them. I found that as soon as I cut those 2 things from my diet I lost 5 lbs straight away. I've also gone vegetarian, but that made me feel like I was sleep walking all day for about a year. And I hate Tofu.
Alcohol. It dehydrates you quite badly, so if you go boozing be prepared to take at least 3 days to hydrate again. My trainer knows INSTANTLY on Monday if I've been out on the town that weekend, because my muscles can't sustain a lot of the lifts I was doing a few days prior. So stay away from the booze. A quick FYI....you can tell if you're dehydrated by looking at your sock lines on your calves. If your socks are leaving big indentations around your legs you're bloated. I was getting caught by my trainer all the time for drinking on the weekend, and that's how he was doing it. Now I wear ankle socks.....
My best suggestion is to get into a routine, and follow it as best you can for a few months. I tend to change mine every once in a while to avoid the monotony of egg whites every morning, and do things like rotate cereal and yoghurt in every once in a while. That way you don't wake up one day and say F$%K this, I'm eating bacon every day the rest of my life.
Oh yeah, if you do my diet plan get ready for some pretty violent mood swings. It cuts a lot of sugar (refined or otherwise) out of your diet, which a lot of people don't even realize that they eat. I went absolutely MENTAL for about 2 weeks, and turned into a raving lunatic when I lost my temper. My girlfriend at the time told me she would rather have me pudgy and calm than ripped and an a-hole.
Good luck!