Recently, I've been taking a four week course on story writing for teens with a friend of mine. It's been extremely interesting, and I would recommend that you take advantage of any and all opportunities like this that you can get your hands on. However, all that is beside the point. The point is that two weeks ago at the course we talked about how to properly start a story. There are three ways that one goes about doing that; dialogue, action, and description. If you have a minute pick up the fictional book you're reading right now, and look at the first chapter. I can almost guarantee you that it will start with one (or a mix) of those three.
My personal favourite start is dialogue, just because it feels like you jump right into the book. However, you must be careful not to begin your story like this:
"What is your problem?!"
"My problem?! Have you seen yourself?"
Although that is usually fine in the middle of a book, it doesn't work out so well at the beginning, because you don't have any back round info, like who the two speakers are. When starting with dialogue you want to make sure that the dialogue has speech tags (said, yelled, ect.), and some sort of action, and thoughts from the main character. For example:
"What is your problem?!" Sally exclaimed throwing her hands up with a defeated sigh.
"My problem?! Have you seen yourself?" I yelled yanking open the dresser drawer, and shoving a pile of socks into my suitcase. Sometimes Sally just didn't understand! I needed a break from this "bonding vacation" that she had suggested we take before I moved away to go to college.
"Just go" She said quietly. I watched for a second as she sat down on the bed back turned to me looking despondent. I almost stopped zipping up my suitcase to apologize, but not this time. I wasn't going to let my sister guilt me into spending one more minute with her self-centered personality.
"Fine!" I yelled. I grabbed my suitcase from the bed and stormed out of the hotel room.
The thoughts are in normal print, the action is in italics, the speech tags are in bold, and the dialogue is in quotations.
You want to make sure you use these four things when starting off you're novel, because you are setting the first impressions of characters, the setting of the story, and obviously you're setting the plot in motion. An example of a published book starting off with dialogue can be found here (scroll down the page, and find expert, click on it and the first chapter should come up)
The second way of beginning a story is action. When you start with action like:
The fire shot skywards with a puff of smoke.
Starting a story with something like this makes the reader ask questions, which will make them want to read on. Let your scene play out, and try not to clog it up with lengthy explanations. For example, you might be opening the story with the main character's house burning down, and you'd want to mention that. However, you don't need to burst into a recount of how they bought the house, and how long they've been living there right away. Let the action finish than you can do some explaining. Resist the urge to explain during the action, because readers can make assumptions from dialogue, (ex. MC saying "All my things are burning!") and other things happening in the scene. Example of book starting with action (scroll down page and under the picture hit read expert.)
The last opener is description. I don't recommend this very highly, because there is a major threat of rambling. It's great that you know a lot about the story, but when you launch into description, especially of setting, the reader gets bored. Although many classics do start this way, those books were written in a different time where a reader wasn't constantly assaulted with distractions, like we are today. You must grab your reader right away, so if you do decide to begin this way don't draw out your description too for too long, and maybe mix it with some action or dialogue. I've found a pretty good example of a book starting with description here (pdf file), and take note how long the description goes on for before getting to the action.
No matter which one of these ways or combination of these you choice to begin your story with, the main thing is to engage your reader. The first few pages is where you pull them into your book, and make them thirst for more, turning the pages until the story is complete. A good start is ideal to writing a good novel!