Greetings,
The missile evading procedures are a lot and always you should know the weaknesses of every missile to evade successfuly. First of all, chaffs are not to be used after you are locked on. Chaffs are little pieces of aluminium foil which make the radar recognise them as a contact. So in real-world you use them to make the enemy track the chaff instead of your airplane. Flares are to be used after missile launch but you have to use them at the right time with correnct angle and Gs. Flares are used to make the missile less destructive. That means that it is not sure you are gonna evade the missile but it is sure that it will make less damage to you.
When comes for radar misslies...firstly when a missile is fired to you you MUST turn your ECM to stand-by. ECM transmits electromagnetic waves to jam the enemy radar so when they fire a missile to you and the ECM is on the missile's radar tracks these waves and follows you. You should also put you radar from norm to quiet or silent. Another good technique is to force the missile overspeed and hit the ground.
That's all for now. If anything comes up or if you need something more special let me know :D