try tons of different expressions on your self portraits. even if you can't hold it, take a pic of it and draw from photograph, then use yoru face for ref if you can't get detail from the pic.
as for sketchbooks, i love your little studies. that's waht we all need to do more. it teaches us so much that we don't get from photographic studies. also if you want to get into illustrations, try framing everything in yoru sketchbook. it will help you later on when you have to frame things in illustrations. you will be used to framing people and object from your sketchbooks! lovin the update goodness! go go go!