If you just launched a missile yourself, you can differentiate incoming from outgoing missiles by which white line is connected to your blue colored aircraft in the center of the display. The white line disappears as the missile moves along its flight path, so the missile connected to your aircraft is the one wanting to scratch your radar-refractive paint job. Once you've identified the threat, you need to maneuver the aircraft so the missile is abeam of yours. This means putting the missile directly off either your right or left wing tip. Diving toward the ground also seems to help.
Drop countermeasures all throughout the process.