You can do the gta 5 bounty hunting / hunter mission after doing the story mission Mr. Philips. Go and talk to Maude at an orange question mark in the north-east end of the desert. This will give you the gta 5 bail bond missions.
Here are the gta 5 bounty hunting target location:
Ralph Ostrowski Location
Larry Tupper Location
Glenn Scoville Location
Curtis Weaver Location
Note – If you want to get the Wanted: Alive or Alive Achievement, you need to deliver one of the bail bond target to Maude alive.