A little advice for aiming (or what I've found to work).
While in binocular mode, and zoomed in all the way, you have a horizontal line, marked on both side should be 1, 5, and 10. If you hold (I can't remember for sure..) Shift or Alt, you can see the enemy ships' health points remaining, how far they are, and the time it will take for the shells to get there.
Now, when you see a battleship which is parallel to you, either going the same heading as you or opposite, and say is 5 seconds away. Place the 5 just at the bow (front) of the ship, and fire one shot (click once) to see where those shells hit. If they hit in front of the turrets, put the 5 just a little bit behind of the bow, and fire the rest of the guns by double clicking. If you can read a ruler okay, then learning the individual tick marks and what numbers those are should be easy.
If a battleship is coming head on, you need to know which of your guns will fire first. Normally it's from front to back but that could be different if your shots are spaced. Anyways, if you have your broadside to him, and he's dead on, am at the bow of the ship, but a little bit left (the starboard most side of the ship) so when your gun travel they hit the side of the ship, not the turrets where they wont penetrate. The procedure is opposite for the back turrets, aim a little right of the ship an you'll hit his right side.
Now, if a destroyer or cruiser is showing their broadside to you... it's gonna be a bit interesting. Generally, it's x2 where you would aim for a BB. Say at 10km away, a cruiser shows his side to you. He's only 5-6 seconds away from you, which isn't that bad. Place the 10 just above the bow of his ship and fire all shots. You don't want to poke one or two shots at a time because he can outmaneuver that. You'll have a large spread and a higher chance to hit. Now, if he's 6-8 seconds, this is really guesswork. Normally I'll place the shot in-between the very edge of the binoculars and the beginning of the 11 line, and hope they hit.
Now if a ship is slanted, it's really all the same. First, if he's 8 seconds away, place the eight at the stern of the ship (it's back). Then, drop your aim to where the aim point is now parallel to the bow of the ship (looks something like _\ _). This aiming is the hardest to do, as any change in speed or direction and your shots are off...
Now, when to use AP or HE. With a BB, AP is your friend until you get close, reeeaaally close. Anything under 4km and you need to fire HE from a BB because you'll overpen. BB's are most effective between 10-13kms, of all tiers, until you get to 9-10. With HE shots, you want to aim for the superstructure of the ship. AP, you want waterline shots, or falling shots where they go straight through the deck. This is when you get citadels and take out everything underneath the ship almost, wrecking their HP by half or more.
I'd recommend you to watch some youtube videos of your choice. I for one find PhlyDaily and BaronVonGamez to be the best, because they do both WT and WoWS. Also, choose your first nation wisely. Japanese have terrible turret traverse rate, terrible accuracy, but the heaviest ships in the game. They are also some of the fastest. The US has the slower of ships, but their reload rate and turret traverse rate is unbeatable. Their DD's (destroyers) are plagued by short torpedo range, but that may be fixed soon.
I chose Japan due to the looks of the BB's, and that's about it. It could be as easy as that, or not... But choose wisely, because the grind is bad.
And I think there were some people on another forum over in EU that I was to run with, man I wish you could just switch servers.
