A sawtooth picture hanger is a great way to hang pictures that weigh less than 10kg. If you have an item that is heavier, you will need to use more than one hanger to distribute the weight.
It gets attached directly to the back of the frame, and from there you can place a nail in the wall and hang the picture from the sawtooth hanger with ease. Many picture frames come with sawtooth hangers already installed, but if you need to do it yourself, it will only take a couple of minutes.