Working on faces

John suggested that I need to look at my faces in more detail and practice drawing them. He suggested I should look at Greek and Roman statues as they capture 
a good expression while looking realistic. I enjoyed drawing from these but I did find it quite hard and 
my responses aren't the best. I think in my drawings I need to focus more on the placement of features as I often draw my lips too far down. 

As my phone broke I couldn't remember where I had drawn the two portraits on the right from but I think they are the most successful out of all the responses. Because I want to start working in print now 
I think to transfer the same tentative expressions I need to firstly draw my work in pencil and shade the important areas and make sure that transfers in the lines of the print.