The Sketchy Sketchbook of ....Sketchyness!!

[clockodile]

Good to you're thinking about your proportion and volume with the siren picture. One quick suggestion for it is perhaps to mix up the tree branches a bit more - they're a bit parallel to each other right now, though you are on the right tracks with how you are making them and the trunk kind of twisted and knobbly. (I don't know if you have a species of tree in mind, but if you don't, look up cypress trees for inspiration, as some of them get that old knobbly look.)