No problem! 
One thing I would ask is if you are using reference - reference can really help, of course, and I think that doing a number of pieces either from reference or from life will really help. The thing I think will tell you the most though is doing a master copy - also, I would recommend a book from the Anatomy Books thread (linked above) such as Hogarth’s Head Drawing book or an anatomy book by another author - any of the books in the Anatomy Books thread come highly recommended.
Down the line I think that doing pages of studies of heads in different positions that analyze the structure of the head are ultimately more useful than doing just one sustained study. Try to get your hands on a good anatomy / drawing book and try some of the exercises contained in them - you might also check out Vilppu’s DVDs, which are full of valuable information. 









