Hi Lisa;
I too have a Collie.....soon to add another Collie when she is
ready to go, she is only 4 weeks old tomorrow.

Bailey is my current Collie, (I've had 4) and Bailey was a leash puller and
a jumper and still is a jumper sometimes when he gets excited. He is only
15 months old at this time. I don't like the head collars for Collie's,
especially the "Halti", I used the "Gentle Leader" by Premier but the head
collars just don't seem to adjust in just the right way for that long Collie
muzzle enough to have them on the dog for much time at all.

Bailey didn't like the head collar either but he was such a leash puller that
for a small amount of time I made him wear it and he did adjust, but hated
the thing all the same and so did I to tell you the truth. What DID work, like
a dream was also by the Premier Co. and it's called the "Easy Walk" harness
and it does fit correctly and worked like a CHARM for the leash pulling and only after a couple of weeks using that harness he no longer pulls the leash.
Instead of the ring where you attach the leash to the harness being on his
back it is on his chest and when he pulled it tightens just with enough pressure that he stopped pulling and there is so much control I could hardly
believe it. Really, I don't recommend any type of choke chain or prong collar
whatsoever, they can be dangerous to the dog. The harness goes around
their body and not the neck it really was a dream to walk with him after we
purchased this harness I was so amazed. We no longer have to use it now.

Bailey has a pretty high herding instinct but doesn't attempt to chase cars
when they go by but when there is a car coming down our street when we
are on walks I make him stop at the same time I say, "Car......wait" and when
the car passes I say OK and then we continue on our walks. Google "Easy Walk"+Premier and take a look at the product information. My next door
neighbor used it on her Lab and it also worked like a dream on him too and he
is a very very hyper dog. Good Luck