I'm not sure if this is how everyone does it but this way works well for me.
My lathe is the Craftsman 15" Bench Top Lathe.
The first step is to find a piece of wood. I mainly use Birch since I can get it free. I cut logs into 1 foot sections then split them down the middle, this will make 2 bowls. Once I have halved the logs I turn them as soon as possible. I try to make them as round as possible before I mount them to the lathe, to save time and keep my knives sharp longer. To mount it on my lathe a screw on a faceplate. That side will be the side that gets hollowed out later so the screw holes are not a problem.
I can now rough out the blank. After the overall shape is finished I make a tennon on the bottom of the blank so my chuck has something to grab when I flip it over.