My two attempts to play Bounty Hunter have been miserable. I've never been able to even transition into the ganking phase because I don't ever feel powerful or capable of killing anyone.
BH can't really kill people solo without big items or if they are at low health or if you have a rune. You need to be doing coordinated ganks on targets with the help of your teammates. Your burst damage as BH is really good, all 3 of your primary skills give you big Burst damage and your chasing is really good if you have Phase Boots plus Orb of Venom. When you are ganking someone, ping the targets so your allies know what's up, hit him while under Shadow Walk to let the Jinada proc, tag them with Track and then just chase them down... use your Shuriken if they try to TP away or if they are just out of range for a melee attack. The Shuriken does a lot of damage but depletes a lot of mana as well so you need to manage it accordingly.
If say you arrive at a gank late and then have engaged on the opponent, then instead of trying to go in with the Shadow Walk -> Jinada hit just tag them with Track from a distance so that you have contributed to the gank. Otherwise your teammate is missing out on a lot of gold. No one hates on BH if he doesn't get some kills but everyone hates a BH who is conservative with his Tracks.
Guys I have a question.
When you are a carry, how do you know when to build Vladimir's Offering and when to build Helm of Dominator?
I have seen Phantom Assasins and Juggernauts using them, sometimes Vladimir, sometimes Helm, but what is the criteria to choose?
If you plan on making a different orb effect than life steal then you must use Vlad's Offering. Like say I want to go Desolator on Troll... I have to build Vlad's because that hero definitely needs the life steal. Same for PA and Juggernaut. You also build Vlad's when there are more than a couple melee heroes on the team especially if they scale late game. Generally speaking you want to have one Vlad's on the team anyway. Vlad's also has a small mana regen component so you get it on heroes who are likely to use some spells frequently. Vlad's is a core item on Ursa because it's the only way he can get life steal as one of his passives is an orb effect. Heroes who have melee summon units like say Lone Druid or Lycan also build this item.
If you want to go a slightly tankier build you go for HotD. HotD allows you to dominate a creep and it's useful for stacking creeps which is ideal for someone like Luna or Gyro who can hit multiple creeps at once (also great on Medusa). Remember that HotD is effective on both ranged and melee carry heroes where as Vlad's only gives the life steal benefit to melee heroes. HotD also upgrades to Satanic which is a great late game item as it gives you a ton of survivability. Shadow Fiend and Drow make HotD as well because their damage is so high that they get a lot of life back from regular hits thanks to life steal. HotD/Satanic is also excellent on Huskar you just need to toggle his orb effects on and off if you want to use life steal.
Mask of Madness is a PURE glass cannon damage item as it gives you some offensive bonuses for more damage taken. You want to use this item in situations where you know you will not be getting hit or in some extreme cases where you want to actually get hit (like carry Abaddon, don't try this strat at home folks). Yeah it gives life steal but it's mostly picked up for the attack speed and movement speed boost (attack speed more than movement speed). It's picked on Void as a core item because he is not getting attacked during Chronospheres and the faster he attacks the more bashes he procs (which do more damage and keeps them stunned for a longer duration). Sven likes to build it because he can stun someone, turn on all of his buffs and kill them before they have a chance to do anything. Magnus can make it because he can Empower, RP then use MoM to do a ton of damage really fast. Snipers in pubs like to build this along with Shadowblade where they will pop out of hiding, turn on MoM and do enough damage into an Ulti before the other person has a chance to react. Drow players make this for the same reason only they add in Silencer as well to make sure their options are even more limited. MoM is paired with Crits/Daedalus because the getting life steal with crits usually results in a lot of life sustain. Spirit Breaker makes this item too as he wants faster attack speed to get more bash procs. If Slardar's Sprint didn't already make him weaker he would pick up MoM too.