Once Hamlet decides to put on an "antic disposition" as he pursues revenge against his uncle, Hamlet is full of confusing deception. Take for example the image of him jumping into Ophelia's grave after she had died and proclaiming boldly that he loved her; contrast that image with the one of him coldly rejecting her, calling her a false woman, telling her to never get married and to get to a nunnery. These two images are conflicting. In one, we think that he hates Ophelia with all of his heart; he is cruel to her, calling her names, rejecting her kindnesses and making her feel awful. He, in that scene, was being deceptive; he was putting on a show for his mother and Claudius, who he suspected was watching. He was letting his mother know, indirectly, how angry her actions had made him. Hamlet, in his cruel treatment of Ophelia, was the image of deception; in reality, he truly loved her, and was devastated at her death.
Another image of Hamlet being deceptive can be seen in his crazy babblings after he killed Polonius; the king demands to know where Polonius's body is, and Hamlet answers with riddle, being difficult, jocular, and seemingly unbothered by the fact that he just killed an innocent man. This is all a deceptive show, meant to emphasize his supposed craziness. It helps to deceive everyone into thinking that he has lost his mind and thus can't be held accountable for killing Polonius. In reality, he is upset that he killed the old guy, even if he did think of him as a meddling fool. But, Hamlet deceives people through his strange and irreverent behavior.
Throughout the entire play, whenever Hamlet thinks people are watching and analyzing his moves, he behaves deceptively to throw them off of his true feelings. And that's just Hamlet; Claudius shows deception in his mourning of his brother, in his behavior with Hamlet (all the while planning his death), in manipulating Laertes into the duel, in offering the poisoned wine. Rosencrantz and Guildenstern show deception in their proffered friendship to Hamlet (all the while spying fo the king). Ophelia herself is deceptive in giving Hamlet his love notes back, and rejecting his love of her. I hope that those thoughts helped; good luck!