I'll be adding lots of examples and ideas to try out soon..and pictures for you to print and colour in.
If you want to improve try taking a sketch book around with you, and practice whenever you have a spare moment.
...here are some more engines sketched with a dip pen and ink and then I added some watercolour
Keep sketching as much as possible. These little figures were done with a pen while waiting at a cafe, for a friend.