It happens all the time. People get a dog and feed him according to the recommended amounts on the bag of dog food and wind up with a chubby puppy. Unfortunately, those directions are there primarily to sell more dog food than to keep your dog at a healthy weight.
On an ideal weight dog, you can feel her ribs, but not see them. She will have a "waist" that narrows where her torso meets her hips and a tuck underneath. Obviously, this is easier to tell on some breeds than others, but these are good guidelines. Cooper's ideal weight is around 60 lbs and I feed him just under one cup of food twice a day, with treats being a rarity.
As far as what kind of food to feed, I'm a big fan of the Kirkland food from Costco. They are corn free, wheat free and have a lot of the extra ingredients pets need and they love them. I use the Lamb and Rice food for Cooper and also as the treats I give the dogs on the trail and 95% of the dogs love it.
I also use a Kong filled with leftover vegetables, meat and water and freeze it for a special treat for Cooper. It keeps him occupied for a long time, without a lot of extra calories.