When drawing a face I think it is most important to make sure the overall proportions are correct before drawing all the details. I know it is tempting to render for example the eyes but if you notice later the eyes are too far apart then you won't want to erase them and your whole drawing will be weird.
Well, you probably know that already but that's the only important thing I can think of. Also my father for example draws a grid on his reference photo and then a grid on his paper, that way you can easily copy from a photo by copying single cells in the grid.
You should definitely post, you're anonymous here remember?