Tips to Use Bounty Hunter (Dota2)

• Track provides a great deal of benefits to the team, the vision and movement speed help with ganking enemies as well as with avoiding enemy ganks, and the bonus gold will provide a big advantage over the enemy team if you get kills. You should try to cast it on every enemy hero, though priority targets should be carries as well as those that can go invisible.

• Despite being a carry, it is generally not recommended to farm when playing Bounty Hunter. Your abilities give you a great deal of power in the mid game, you should use this time ganking enemies as the bonus gold from Track more than makes up for the farm you may miss.

• Although it provides a great deal of benefits, Battlefury is not always the best item to get since it's main purpose is to farm. It may be better to opt for an Orchid Malevolence, Medallion of Courage, or other such items that will help you gank better early on.

• Although not always recommended, Shadow Blade can be useful for damage stacking. Using it and quickly Shadow Walking will give you +270 on your next attack, combining that with Jinada can heavily wound an enemy.

• It is possible to get the bonus damage of Shadow Walk twice by attacking once during the fade time and once to break the invisibility. This can help securing last hits or harassing. 

source: http://dota2.gamepedia.com/Bounty_Hunter