The Tier XI USN Battleship, Iowa. Iowa is armed with 9 16"/50 Mark 7 guns, which can be upgraded to 16"/56 guns, in 3 turrets of 3 as her primary armament. Her secondary battery, which can only shoot AA ammunition, consist of 20 5"/38 guns with 10 on each side of the ship. The last (as of this writing) battleship in the USN line, she is fast, heavily armed, and in capable hands, can wreck havoc on most large ships, although she does have trouble with faster ships. The Iowa-class BB's where commissioned in 1943, 4 of the intended 6 were finished, Iowa, New Jersey, Missouri, and Wisconsin. They have been used in every major conflict the US has been involved in from 1943 until 1991. In the 1980's all four ships were modernized with Tomahawk missile launchers, Harpoon Anti-Ship Missile launchers, CIWS 20mm Gatling Cannon defense systems, and spotting drones for their main guns, replacing most of her secondary armaments. Missouri and Wisconsin both bombarded Iraqi positions during the Gulf War, marking their probable last combat use in their long careers. All four are now museum ships open to the public.
As you have learned in the North Carolina and the South Dakota, you should not go and run straight into the fry, if you do this, you'll just end up getting one salvo off then give the other team a massive damage boost. The best tactic is to stay farther back, keep your scout near the end of your range, unless, of course, you see an opening and opportunity to flank them or a clear shot to the enemy CV. Your guns aren't the most accurate, but they are better than North Carolina and South Dakota, and they do get better after you upgrade to the 16"/56. You should find a distance at which you feel you can hit most ships and remember the elevation your guns are at and try to engage at that distance if you can. Your not much good to your team if you can't hit the enemy your shooting at. (Remember, you don't have much ammunition for your main guns, in some longer battles you may run low or even out, especially If you shoot at DD's and cruisers at your maximum range.) Since your most likely one of, if not the, largest ships out there, some DD's and CL's will try to make a torpedo run at you, keep your speed up and shoot once they turn broadside to unleash their torpedoes on you so you will hopefully be able to get enough hits on them to sink them and preventing their torpedoes from launching. Make liberal use of the 'E' key if your are on Auto FCS. You are the fastest BB in the US line, use that speed to maneuver your ship into firing positions and get to where your team needs you the most. Being a tier XI BB means you bring a large amount of firepower to the fight, you need to place it where it will make the most difference in the battle, don't rush into a group of five or so ships, most times if you do this you will end up under the waves. Just because your large, doesn't mean your invincible, remember "The bigger they are, the harder they fall."
What you put on your ship all depends on what you want to do with her. You can load her down with armor and you will be a lot tougher than normally, but your speed will be cut severely. I prefer to keep 1 Deck and 1 Belt armor on mine so I can still cruise at 30 Knots, while still having some cushion for my hull. You could also load Iowa down with Enhanced FCS and sit at the extent of your range and act as floating artillery, supporting your team from the rear of the battle if you prefer to do this.