DCollie is coming up 4 months and has only just started to love her walks, harness works best for her, we have been firm with basics so far sit/ walk on at the curb and the is helping when she messes about on the lead, at the moment we are working on heel and keeping her attention on us rather than cars etc
A ball to throw a couple of paces ahead or kibble gets her focused on moving in the right direction as needed
If she is too full of bounce to concentrate a short run (cause I can't do more than that) takes the edge off.
Sit! also stops the jumping/mouthing she tries to do when over excited
Am going on the same theory as small children, distraction from bad behaviour, reward for good, simple commands and consistency from me and DH
Did read somewhere, very likely on another thread that a bored collie is a bitey collie and they are at their best when mentally stimulated, may be the same for your cross