Ive been playing SH3 for a month now and still havent started a campaign. Im training in single missions trying every possible scenario, angle, tactic etc. I play 100% realism with GW+NYGM+EUC and some other mods. Im firmlly convinced that harder settings right from the start and good practice make things easier in the long run.
There are the basics that you need to understand first: the dependecy between bearing, target course, speed and angle on bow. Once you understand how things work you can go one step further and so on. Youll find yourself guessing speed and AoB without a hitch
Practice, practice, prractice.
If i recall corectlly theres even a 7P rule in the US Navy:
"Perfect planning and practice prevents piss poor performace"
Cheers!