If there's no flaw in any of the subsystem of the missile then just improving the attrition rate (successful hits/total fired) is what's left. Now this can be done in multitude of ways from firing a salvo to catching the enemy off-guard to using it together with other weapons.
It'd be impossible to get the actual RoE without a leak...at best, we can just guess the most plausible one based on our own knowledge
Radars on vessels, coast, P-8I, satellites, SONARs, HUMINT, ground troops provide the GPS vector of the vessels. Missile is fired at that. The seeker turns on and matches the returns with it onboard library to lock on or in case it's not known then goes for the most lucrative one.
As of now we've multiple radars types, over the years military satellite tech has matured quite a bit, there are SONAR listening arrays, aerial radars are there too in terms of sensors. As for effectors; the first layer of defence would probably be (1) Agni-II, followed by (2) Agni-P, then this (3) LR-AShM, (4) BrahMos and lastly (5) SMART.
Though technically (3) is from where you lose your advantage of overmatch and start to come under the range of Chinese ship launched cruise and ballistic missiles.
So as of now we have quite sufficient number of solutions to counter PLA ships except for one and that would be the hypersonic cruise missile. But hopefully soon we'd hear about that too. On a more practical basis the only thing that we need now it producing these in good quantities; going back to where I stated this post...you need to improve the attrition rate.