I gained 60lbs with our wee one. Then another 30+ over the next 8 years. It's taken me two years of hard work to finally get back down to a healthy weight, 101 lbs gone!!
I've pretty much been doing what LunasMomma said. Only I needed that extra support and accountability. So I joined Weight Watchers online, but switched to meetings shortly after. It's "slow", but healthy. I've been using the time to learn a lifestyle rather than dieting.
As for a quick tip...
Don't starve yourself. Drink LOTS of water! Espeically if you're exercising or nursing. The way it was explained to me was to think of your body as a car. Your body needs fuel to run. The better quality of food (fuel) the better your body runs. Exercising and nursing cause the body to burn through the fuel quickly. When you don't refuel enough, the body will refuse to give up any weight. It goes into a starvation/survival mode. Giving your body the better fuels/foods convinces it you can take care of things. Then it's more likely to give up those reserved fuel cells (fat).
Whatever you do, don't give up!! You're worth it!!