Of course when or if you want to get published you will want to figure out your target audience and all that good stuff, but at first write just for yourself. Get your words out and onto the paper. I think with all the zillions of blogs and websites and words of advice about writing out there it is so easy to get sidetracked and forget about actually writing. You might start out sitting in front of your computer, all ready to write then you think I'll just pop in and check out that blog. Next thing you know you have linked to another writer's site and enrolled in a webinar. Before you know it the morning or evening in my case is gone and what have you written? Nothing. I am just saying focus on writing.
And be very careful and picky about which writer's sites you choose to visit and spend your time at. Sometimes we can be influenced by things very subtly and not even realize it. When you find your voice, and you will know, keep it. You know that feeling when you are writing and it just rings true, maybe you get that little tingle in your stomach like I do, to me that means I found my voice and I am writing in it.