I used a couple different pens on this. An ink marker for the ones on the bottom, and a ball point pen on the top two. There's a little Mushu that crept in there too.
What I like about your sketches is that you can see that you love your work, and it is always cheerful, (even the sad girl is drawn in an innocent, cute way) which must be an expression of your personality. Not enough positive energy like that in this world. Glad to see it and I hope you always are this positive and enthusiastic about life.