Walk everywhere, within reason. Twice a week I walk the 12 miles home from work, the rest of the week I walk the 4 miles to the city centre and bus the rest of the way home. If you walk to somewhere like the supermarket, if there's a longer route available, go that way.
No alcohol, or if you really can't go without, save it as a Friday/weekend treat. I absolutely piled the weight on through booze and I'm really trying to shift it, but in all fairness I was drinking seriously questionable amounts - far, far more than was healthy.
As others have said, cut out processed food. Don't be afraid of cheese and butter, but be mindful of how much you're consuming.
I drink loads and loads of fizzy water, as plain is a bit boring. Also fruit/herbal teas are good.
Eat lots of fish - I find a mackerel fillet in a wrap with some spinach, cucumber and hummus is good for breakfast, the protein keeps me going til lunchtime, which I was amazed at as normally breakfast makes me ravenous within the hour!
Homemade meals like chickpea and spinach curry or 3 bean chili are cheap and quick to make, really filling, and even though there's no meat in them (both recipes I use are vegan) you don't feel deprived. Eat either with rice or as a jacket potato filling. I'm not vegan myself but I do find that a lot of vegan recipes are inherently low in fat, and it encourages me to try foods I wouldn't normally consider.
I think it's important not to deprive yourself though. If you want chocolate, eat the chocolate, but once again just be mindful of how much you're eating. Eventually it gets to the point where just one chocolate is a lot more enjoyable than a whole box even though I could still happily eat a whole box.