Drawing the rose freehand gives you more relaxed and energetic drawing, but you need to be able to allow for imperfections and not become frustrated by lack of accuracy later in the process. When freehand drawing, I still work from the inside-out, but will keep interior detail fairly minimal until I've loosely sketched the whole bloom and stem, so that I can adjust proportions if need be.
If working from a photograph, if accuracy is important to you, you can go ahead and trace some guidelines if you wish. Work very lightly at first and be aware of highlights: the edges of the rose petals are light, so you don't want them outlined in dark pencil. I use the red colored pencil to very lightly sketch the main shapes, working from the inside out. The actual drawing is much lighter, I've darkened it so you can see it.