Well, you’ve chosen a nice hard one to start with, since heads and faces are generally some of the hardest modelling tasks to get right, especially if you want to do it “properly”! If you’re just beginning, I wouldn’t worry about getting it perfect first time, but it’s worth remembering that there’s a real art to it that will come with a lot of practise and learning. What I’m trying to say is, don’t get discouraged if it takes a little while to get the hang of it!
For getting started, I’d say to apply two modifiers quite early on - the mirror modifier and the subsurf modifier. Since faces are symmetrical, the mirror modifier is really useful for pushing and pulling verts around on one side or the other. The subdivision surface modifier automatically adds more geometry in a smooth fashion, and I find it quite useful to have it on from the start so I can drag vertices around and see how that affects the curved surface. If you’re having trouble seeing the vertices under the subsurf’d mesh, you can uncheck the “eye” icon turn it on and off.
I’d recommend getting to grips with the basic modelling tools - extrusion, subdivision, loop cuts, etc. Blender Cookie has an excellent (and, I believe, free) intro course that’ll get you up to speed really quickly: https://cgcookie.com/flow/introduction-to-blender/
If you’re looking to sharpen your skills further with mesh modelling, I’d really recommend Jonathan Williamson’s Mesh Topology course - it’s a bit old now, but the core techniques haven’t changed: https://cgcookie.com/archive/learning-mesh-topology-collection/