The eating side of stuff is often hardly worth asking others - everyone will have their own "system" and crap like that, the ones which are most effective are going to be largely untenable if you hope to maintain any kind of social lifestyle. Whenever I had a live-in gf I'd be 10-15kg overweight simply because of lazy social eating - eg having big dinners for the sake of having something to eat - whereas when I'm by myself I don't even think of food unless I'm actually really hungry.
The only real solution which can work for anybody who's not a major exerciser is the simple good old moderation. The people that tell you don't eat this or that cos it's "bad" for you shit me off - sure, if that's all you eat - but I've never got fat off a single meal.
Most people's bodies are great at digesting any sort of junk you throw at it and turning it to energy - by now you know what makes you feel good - I'm not talking about just the taste and the act of stuffing your face, but the next 6-12 hours. People look at the steaks I eat and it makes them grimace - fact is I feel really good for the next whole day after a good dose of blood and meat, whereas when I have a Hungry Jacks burger or meat pie I feel like crap for the next 12 hours or so - but I sometimes really crave them (usually after lots of drinking the night before) and it's worth it to satisfy it.
Aside from that though, 90% of my meals are just normal healthy crap - tuna rolls, muesli, caeser salad, chicken & capsicum, stir fries, etc, plus I drink heaps of juice - I really love V-Plenish Citrus Splash, and according to the labelling a cup of that is equal to 1 serve each of fruit and veg.
Things to cut out are the grazing stuff that you just consume randomly during the day at the desk - crisps and soft drinks - I'll never deny it when I'm out at a function or whatever, but sitting there at the desk munching away and sucking soda (even the "diet" stuff) is the one that does crap to you.