My squad and I have been tampering with different wingman tactics for a while and usually run 2 man wings that can easily be made into 4 man.
First we just started going in hot and communicating to try and bait the NME.
This works well, but we started a new way that seems to keep us alive longer.
One lead, one trail. Distance depends on E state, the fighting style, and aircraft. Basically the trail will always cover the lead's six. That way the lead can be more aggressive with his opponent. Because Either he will be lining up on someone's six, or getting ready to give his trail the kill. There's a lot more to it (when to switch lead and trail on the fly, when to close, when to keep distance and so forth), but this is just a small gist of it. It makes it a lot easier to stay together when the trail only has to focus on his leaders six.