Bounty Hunter is the same concept as old pking.
you just wear whatever you did before and go to edgeville and fight people
One major difference is theres no item protect prayer anymore, so if you want to keep 1 item you can go to the BH+1 world to always keep one item.
Or you can go to the regular BH world and risk it all.
In order to get a decent drop you need to have a 75k+ risk for p2p, and the person you kill needs 75k+ risk, also killing the same person over again will result in a junk drop, so keep that in mind.
There's also targets, every now and then it'll give you a target. This is a person with an arrow over their head that you are supposed to fight.
They can attack you right away even if you're not in deep enough wild, and if you're in the middle of a fight. You can do the same to them.
Killing a target results in better loot than a regular kill, also no risk is required for target kills to give good loot.
Lastly, there's EP. (earning potential) this determines weather you can get good loot or not. Usually it goes up by 25% every 30mins you stand in the wilderness with a 75k+ risk. Having anyting over like 20% ep will usually result in a good drop. Providing that you've lost some recently.
In PVP/BH now you have to lose money to make money, but you can still make profit.
Hope that explained it enough :\