It is always beneficial to study and master anatomy, even as a caricaturist. It gives your drawings a better sense of structure. When drawing quick life drawings at events, the structure will not always be perfect, but it will still have a more life-like quality.
Seek to improve the quality of your line work. Whether you have a more smooth flowing line style, or a rough sketchy one, make it consistent and well defined.
Learn to draw the face from a variety of angles. Attack that three quarter view!
I will give more tips soon.