Here's a link to 500px.com where I did a keyword search for "carrying bag:" https://500px.com/search?submit=Submit+Query&q=carrying+bag&type=photos
You should find some good ideas. I'd also encourage you to use a better looking bag than just a white plastic bag from a grocery store.
Having items sticking up from the top of the bag is a commonly used way of showing the usefulness of the bag. Having someone hold the bag adds that human element which adds quite a lot to an image.
Think of a time where you use the bag, and then set up a scene to tell that story. Maybe it's a boy walking with his father each with fishing poles on their shoulders. The boy is holding a bag with fish.
Maybe you could have two friends about to make dinner together and one is pulling a bottle of their favorite beverage out of a bag and giving it to their friend.
The idea here is to get away from the sterile product shot and instead, tell a story with the item.