My preferred playstyle in Elite: Dangerous is that of a bounty hunter. I suppose this is mainly because of a childhood (mis?)spent watching the original Star Wars trilogy and idolising Boba Fett. That said, the role of a bounty hunter in Elite: Dangerous isn't clear cut, but can be broadly categorised into two sub-types of bounty hunter: the FSD Interdictor and the RES Hunter. I'll write more specifically about RES Hunters in my next guide, as even though the roles might appear superficially similar in that they both kill crims for cash, they do require distinct loadouts and potentially different classes of ship.
An Interdictor Bounty Hunter (or as I like to call them, an Interdick) needs two key pieces of equipment in their loadout: a Frame Shift Drive Interdictor module (well, duh!) and a Frame Shift Wake Scanner. A Kill Warrant Scanner is useful, but arguably not essential. If you're flying with a ship that only has one Utility hardpoint (i.e. an Eagle) you will have to make a judgment call as to whether loading out with a Frame Shift Wake Scanner or Kill Warrant Scanner will earn you more money, since you can't fly with both. Personally, I'd take the FSW scanner. Also essential for the burgeoning Interdick is a ship with good firepower and long-ranged hyperspace legs, because more often than not, the suckers you yank out of Supercruise will try to run. Therefore, you either need to be able to blow their Frame Shift Drive out from under them before they escape, or simply be able to out-range their hyperspace jumps. The latter of these two options is decidedly easier than the former.
In each of these guides I'll post three ship specs for the role, each one in a different ship model, for three budgets. The "low cost" option will not exactly be bargain basement, but will cost less than 2 million credits, so I am assuming you've had a little time with the game to build up some working capital. After all, it's not hard to get yourself over to E:D Shipyard and spec your own minimum cost Sidewinder for each of the roles. The "mid range" option will assume a budget of between 10-15 million credits, for those established players who want to try out something a little bit different, and the "high end" option will assume that money is no object at all, and that you've got 50 million credits and upwards just burning a hole in your account with the Bank of Zaonce.
Interdick Eagle - 1.9MCr
I've undoubtedly mentioned this before, but I love the Eagle. It's a lovely little ship, and if you don't mind the fragility of the hull and the power management required to keep the modules up and running at the right time, then this spec is ideal for NPC interdicting. The only real issue with the Eagle is the lack of a second utility mount for a Kill Warrant Scanner. This can be a problem if your quarry jumps out into an anarchy, because that juicy bounty they had in civilised space will disappear faster than a plateful of cake in a high school staff room. The gimballed beam on the dorsal turret will strip your target's shields hopefully before they can return the favour (just remember to pop your shield cells nice and early - don't wait for the warning beeps), and the cannons can target and pound the hell out of the FSD of the target, hopefully before they can spin up into hyperdrive, so they you can take them to pieces at your leisure. And if your mark does get away, a hyperspace range of almost 18 light years should allow you to catch up with most NPCs. The Eagle's maneouvrability is key to making sure the enemy doesn't lay too many gloves on you, and also ensuring that those cannon rounds hit the required subsystem, rather than do too much hull damage. I first tested out the game's interdiction mechanics using an Eagle with a loadout similar to this, and I was taking down NPC Pythons pretty much with impugnity. Just on general principle, you should keep an Eagle in your starship hangar - they're just too much fun, and cheap to replace if you boil one.
Interdick Cobra Mark III - 12.8MCr
I agonised a bit over the weapons loadout here. I did consider plasma accelerators (briefly), but I think the projectiles are a little too slow and easy to evade to be used effectively for an interdiction vessel, where your target may be on the run. The gimballed Class 2 beams do good damage against both shields and subsystems, and the rail guns can be used to get critical hits on either the FSD or power plant of your target, ideal for quick kills. The 22 light years of FSD range is adequate for just about any NPC you'll encounter and the A-rated Shield Generator and array of Shield Banks should keep your hull out of trouble. You will, however, need to actively manage and restrict your module use, because with everything turned on, you're going to be significantly over your power budget. However, it is possible to keep all the vital combat systems running, provided you only use the scanners when you need to and only have one shield bank activated at a time. Likewise, the fuel scoop is only required in supercruise if you need to top up before chasing down your target, so will not affect combat. Also, if you ever get bored of bounty hunting, the Cobra is really easy (and relatively cheap) to re-spec into another role.
Interdick Asp - 44.75MCr
A lot of people underestimate the combat potential of the Asp, probably because it comes from the same stable as the venerable Space Cow. With a grand total of no less than six weapon hardpoints, however, the Asp does have a lot of stopping power. Its other great advantage as an interdiction vessel is a large power plant capacity, the longest hyperspace legs of all (barring a bare-bones Anaconda) and lots of space for utility and combat support hardware. Even with the big power plant, this spec does still require a bit of active module power management, provided you don't want everything to shut down when you deploy your hardpoints (because we all know how much fun that is in the middle of a firefight!). In combat, an Asp with four gimballed beam lasers on the Class 1 mounts is really something to behold - beware the laser fingers of death lancing out to grasp your target! Then you've got the dual gimballed Class 2 cannons to pulverise the FSD or power plant from close range. And it doesn't really matter if your quarry jumps away, because with 27.5 light years of hyperspace range, nothing's going to be outrunning you (not if it's an NPC, at any rate). And the kicker? You've even got a little bit of cargo rack space to scoop up anything juicy the target space poops out of their cargo bay to sell on the nearest handy black market, too. The Asp is a really versatile ship and I like it a lot - you're going to be seeing it rather a lot in the guides to come.