Millions of women shed pounds with Weight Watchers® by following a point system that assigns a number value to food to help people make healthy choices (carrots, good; Quarter Pounder with Cheese, bad).

Susan Hunt Stevens has taken a similar approach to going green. The Newton mother of two recently launched Practically Green (http://practicallygreen.com), a clever website that shows people how to take steps to improve the health of the environment and their families by assigning a value to different actions.

Newcomers take an initial quiz to gauge how green they are, earning anywhere from a Level 1 “Barely Green” to a Level 10 “Superbly Green.” Then they work toward accruing points to improve their score. Install smart power strips and earn 10 points; plant a garden and get 20; line dry laundry in the summer and tack on another 25. Followers can post their scores onto Facebook and compete with friends for points by making public promises to follow the speed limit, reduce showers to five minutes or less, or drink locally brewed beer.

They can also earn badges for things like taking a Green Date Night – walk to a restaurant and order organic wine.

In honor of Earth Day on April 22, we recently caught up with Hunt Stevens to help us grow in the green department:

1. What was your quiz score?

The first time I took the quiz, I was a seven. Over the last year and a half, we have done a lot of work on our house, and now we are at a nine. We installed a cool system that generates electricity back to our house and we did a lot of insulation. I switched all my skin care. I’m still in the market for an all-organic blush and mascara, and we have work to do on our gas bill.

2. What’s the hardest thing for people to change?

Anything that requires a significant capital investment, such as upgrading to a high-mileage car, can be daunting. I think the ones that are also hard are those that require consistent behavior change. Turning the lights off, turning the water off when you brush your teeth, taking your shoes off at the door. You can’t change behavior until you make it a habit.

3. Back up for a minute. Why take off your shoes?

This is one of the easiest, most practical things a person can do. By taking your shoes off at the door and not tracking in dirt and debris you reduce indoor toxins by about 80 percent. The other one is to cut out meat one day a week. This change is like driving a hybrid.

4. Anything you are doing today that surprises you?

If you told me five years ago that I would be shoveling a 30-yard path in 70 inches of snow to take my two gallons of garbage out to our compost bin, I would have suggested you stage an intervention – aliens had taken over my body. But today we only put out our garbage bin every two weeks and it only has one bag in it. We have really cut our garbage and that feels good.

5 How do you react when you’re at someone else’s home and they throw plastic water bottles in the trash?

Our goal is to be smart, practical, fun and passionate, but never preachy. I might take the water bottle I was holding home to recycle, but I don’t go digging through the trash. It’s not our job to be critical. We are saying, ‘Here are ways to improve.’ For me it’s my gas bill. For some, it’s the length of their commute. For some, it’s juice boxes. That’s why we’re called ‘practically green’ instead of ‘perfectly green.’ But it does kill me, I have to admit it.

Susan Flynn is associate editor at the Boston Parents Paper. She can be reached at susan.flynn@parenthood.com.