Use Alt 2, put crouch on toggle, put aiming on 'hold', and put the sensitivity to one below the middle for both axis, but have the 'high precision' toggled on. My DS3 analogues are well worn in by now, makes for very comfy aiming. It's the only tolerable setup for me, even though melee is useless in this scheme because it's mapped to R3. Meleeing is pretty pointless anyway, so I wouldn't worry.
Basically, don't use iron sights much, they're not that effective unless at serious range. Instead, just do minimal burst fire, longer burst at closer distances. Plus, aim for the head. And don't forget the magnum, if you're 1 on 1 and you waste a clip without killing, whip out the Magz. 2 hit kill, 1 if you've already shot someone a bit.
Most people don't get how to use their weapons on this game and so I reap the benefits. The only tolerable gun is the main ISA rifle.
The amount of shotguns users is ridiculous, but on the whole they make for entertaining kills at distance because they can't do shit.
Play as tactician, make sure you put your spawn points the right way round, and have your second ability as air support/boost depending on map size and objective.
dwarf out.