There isn't a magic solution that works in every possible scenario, but there are some best practice you should follow. Keep the emitter at 90 degrees (correcting your heading if the emitter change its) and fly close to the ground are definitely the best thing you could do to break a lock.
There are a couple of things you should always keep in mind: whenever the missile lose the target, it'll start to fly ballistic in a straight line looking for a new target and getting closer to the last tracked position. If you don't leave its field of view there are chances it starts tracking you again, turning on your tail and reducing its Angle Off Tail.
That's what the chaffs are for, when you manage to break a lock or the emitter is struggling track you they should be used to give you enough time to leave the tracked area.
Anyway, there are situation when trying to break the lock is not even your best option. Missiles' engines have a really short burn time and, unless your ECM is on, missiles' tracking algorithm always try to keep their flight path in lead pursuit to manage the energy efficiently (they always try to predict the impact point for your current flight path). So if you force them to keep changing their direction while they are gliding, you can bleed all their energy before they get close.
One last thing you should keep in mind is: in most cases you can outmaneuver a missile, so a last second hard turn in the right direction, with a couple of chaffs if needed, could save the day.