On to the build!

Equipment:
Armor : Well, I use my normal armor, which has +3 Marksmanship in total, and +1 to everything else. I dont see the need to boost everything into beast here. There are not enough beast master skills to really warrant that.
Weapons: Now, you have a choice. If you decided to use Marksmanship like this build does, then go with a bow, obviously. But if you want to poor more into your beast and just stand back and cast, go with a staff.
Usage:
I tend to just target an enemy with the pets mini bar and have it stay on that target. I use Ferocious Lunge as often as I can, and use Poisonous Bite when I need it. Then I cast Necrosis as needed, as well as Finish Him and Pain Inverter. I also keep Otyugh's Cry up, so my pet is a better tank, and cannot be blocked, meaning I always get energy and poison. If I have a bow, sometimes I just attack a second target while my pet gets the first.
Really, not much more than that. Very similar in spirit to the Haud Dissolutus Build of before.