I'm not sure if you watched these tutorials yet, but here are two on corners:
PatrickHDxGaming -
https://www.youtube.com/watch?v=8bO2YNzJbqI
TMMgamer -
https://www.youtube.com/watch?v=dLWu_mTw3rc
I'll just make a quick note on corners for you based on my own experience:
1. Use a left-footed player for the right corner. I play with Manchester United, so a lot of times I use Van Persie for this. The idea (if you follow the TMMgamer routine) is to curl the ball with spin towards the goal. He explains that this helps keep the defense off balance and gives the attacker an edge as they are moving towards the goal when they take the header. It makes sense to me.
I have scored with this routine quite a few times, and often they have been important goals.
2. Physically look at the controller in your hand when you practice corners to get a handle on where the left stick is being positioned. I have a tendency to put too much top-spin on the ball - i.e. don't push the stick far enough to the right or left and too much to the top. This is usually why my corner kicks don't hit the position I want them to.
Once I kind of "train" myself on the positioning aspect, it almost becomes like second nature. Every once in a while I practice this, though, because I do tend to go back to my old habits.
3. It's better to go a bit higher on the power than it is to go lower. Rarely do I score if I power at 2 bars or less. I am probably most successful around 2.5 bars, but I have scored at 3 bars and maybe even higher. I've just found it makes sense to err on the side of more power.
4. Go easy on the header button. I know everyone who reads this will probably already know this.
5. I have no tips on fighting for the ball! That's part of my issue on crosses. I also have nothing to say on PatrickHDxGaming's corner routine because I haven't used it myself yet.