Don't worry about your "style". Just have fun drawing. Your style is like your handwriting, it comes through while you are working. I think we sometimes confuse medium for style. The medium you choose to work in will give your work a certain look, but your style will translate into any medium you choose because it's your natural form of expression.
Don't get too precious with your sketches. I see some artists freeze up, working on only one piece. It's been noted that great works come from artists who produce lots of work, some of it mediocre. While those who work trying to create that "masterpiece" never give themselves the chance to fail, and consequently to grow!