The grid method is the oldest reliable trick in representational drawing. Instead of judging a whole face at once, you divide the reference photo into equal squares, draw the same squares on your paper, and copy what you see one square at a time.
It works because your eye is very good at comparing small shapes inside a known box, and very bad at estimating long distances across a page. A nose that looks 'about halfway down' is usually placed far too high — but inside a single grid cell, the same nose is easy to place correctly.
Start simple: overlay a grid on your reference, choose the same number of rows and columns on your paper, and letter the columns A, B, C and number the rows 1, 2, 3. Say the cell out loud as you work — 'C4 has the corner of the mouth entering from the left edge' — and the drawing builds itself.
Two habits make a big difference. First, draw the biggest shape in each cell before any detail. Second, keep checking edges: where a line crosses a grid line is a fixed landmark you can trust, so put those crossing points down early.
Once proportion stops being a struggle, you can spend your attention on the parts that actually make a drawing good — value, edges and mark-making.