great work! you're definitely on the right track, I would advise you to do a lot of lay-ins first using both Loomis and Reilly method this will make your basic sketches look more 3D, leave the features for later, ill give you a quick example first put the reference in the middle, duplicate that layer and put it on the side, do a basic tracing of rhythm lines this will let you know where your lines are exactly supposed to be then do it freehand, and while drawing make sure to compare your drawing to the tracing you can also do lines from the forehead and nose/mouth on a separate layer and turn it on and off to see if you got the proportions right . I've learned all of this from Angel Ganev highly recommend watching all his YouTube videos download his brushes and reference pack and start doing the exercise you'll notice a lot of improvement! remember don't focus on the features the purpose of this exercise is to make your sketch look 3D and have clean lines don't rush it it takes some time.. and most importantly have fun!