You should develop an art style first and foremost. Afterwords, find out how to translate that art form into a game environment.
Look at this link, or rather, the artwork within it.
That looks NOTHING like a Zelda game, yet it's the precise style they are using in Skyward Sword. You can't rightly tell for a very good reason (unless you have an eye for this). The reason lies in the difference between a book and a movie. Between art and moving art (or a game for example) things have to change to match itself (I hope that makes sense).
Now when it comes to tiles, you have to comprehend that the style of art you want might not work well as tiles but it CAN be incorporated if you take the time to do so. Artwork for a game is its own project, and not something to take lightly as a side-issue, but a full-fledged "needs attention" part of the process.
For this very reason, as a game developer and semi-okay artist, I like to take graphics from other people. I use placeholders and once I have a game how I like it to be, THEN I focus on drawing my own art for translation into sprite form.
I hope this helped!