Look out! It's still something I have to make a concentrated effort on to do well, possibly because of a poor scan technique. Make an effort to always be searching for aircraft, and to try and find ones who have given a position report in your area. It takes time to learn the art.
There's the story of the WWI ace Eddie Rickenbacker being taken up for his first flight at the front and being asked how many enemy planes he'd spotted, of which he’d seen none. Then being informed there'd be a considerable number and that he had a lot to learn. (which it would seem he did!)