Hasta La Motion!

I am trying to get into Nuke more, as I used After Effects for most of my Keying and Roto and have taken classes on nuke from fxphd but trying to do some work on my own stuff as I go through the classes.

i am going throw the keying class in the First nuke class but cant seem to get a nice key for this shot. I know I could just use roto but I wanna see if I can key it first.

The main probably is the edges are very rough when I key, just looking for some suggestions on ways to tackle this in Nuke, Still getting used to the Node based layout .