In general, there are two ways to write the first draft: Plotting and Winging It. Other names for this are Plotting and Pantsing. Plotting is where you plot your entire novel out before you actually being writing. Pantsing, or as I like to call, winging it, is just that: writing whatever comes to your mind, staying within the plot, of course.
Personally, I find plotting fun (most of the time), but when it comes time to write, I feel like its all down on paper and there is no need to elaborate. I like to come up with a general plot, what the problem is, and a few other major events and just start writing. Also, I come up with most of my characters ahead of time and spend some time getting to know them.
Do you plot or wing it? Vote just above the About Me section on the right side!