Dialogue can be a really important part to the story as it furthers the plot and conflict, fleshes out the characters and reveals some of their traits, beliefs, mannerisms, etc. rather than you having to 'tell' your reader about them.
If you feel that your dialogue is cheesy, then you need to make the speech more natural. To get the dialogue to flow and sound realistic, listen to how random people talk in everyday life. Get a sense of their natural speech patterns, listen to the way they talk, how they raise subjects, where the pauses are when they speak, the tone and particular words they use, and so on.
While dialogue is like real speech, you don't want to bore your reader with the unnecessary and meaningless prattle, so cut out anything that isn't essential to the story or the character development. Remember: everything in your story should have a purpose and shouldn't just be put in there for the sake of it. Dialogue is much the same; it needs a purpose or it becomes pointless. Relate all your dialogue back to the point of the scene. The point of the scene may be to further the plot, to develop characters, to reveal background information, and so on, so make sure *all* your dialogue has a purpose within that scene. If it doesn't, scrap it.
Break up your dialogue with action. In real life, people (usually) don't just stand there and talk, especially if in a pressured situation, which is something your character might be in. This is where the 'listen to how random people talk' thing comes in again. Hear where they pause, look at their expressions, listen to their tone, watch for any action/physical movements they make. All of this could help you when it comes to writing for your characters.
Finally, I would recommend visiting this site to get more information on improving your dialogue: http://hollylisle.com/index.php/Workshops/dialogue-workshop.html . It's a free, online writer's workshop by the author Holly Lisle, in which she addresses the issues surrounding dialogue. Also, I'd highly recommend checking out her video review/critique/lesson on dialogue on this site: http://howtothinksideways.com/crashtests/writing-videos/holly-lisle-and-the-case-of-the-ghostly-girls=/ . Once on the site, scroll down to the second entry from the top of the page, entitled 'Holly Lisle and the Case of the Ghostly Girls'. In that video, she reviews the dialogue of a piece sent to her and shows the viewer what was wrong with it and how to fix it. It's helped me with my dialogue so much.
Well, I hope that this has helped you! Good luck with your story :)