I'm a stang driver; and when I see an FW (or anything else lately) at any alt; I tend to go to 'red alert'.
If pressed from behind, use the outstanding roll rate to get into a scissors. The AH FW is more than generous regarding min controlable airspeed and stall.. you can easily force most contenders out in front, or sweep em off entirely to a high go-around. Use the tools you have that they don't. Wicked accel; fast roll; excellent vis and rugged airframe can combine to simply wear the other guy out. Which brings me to the best part.. the pilot.
A mark of an excellent FW pilot is agressiveness, tempered with very good SA. Don't underestimate the fear a front on view that an FW instills in your adversary. He will give you plenty of room; or get a dose of 'old faceful' if he doesn't. Put the fight in his face ASAP.

Remember to fight in the vertical. Stay away from flat turning. Practice near stall rudder over (wingover); or better yet the snap roll. Near stall; nose up sharply, close throttle gently. At stall, open throttle sharply to WEP; right aileron & right rudder, hold stick back. Wallah!
Prime rule of engagement in AH with any E fighter.. : ATTACK DOWN; EVADE UP. Don't pretend to be anything other than what you are.. the biggest fastest cannon truck ever built on the continent. Fly it that way.
Fuel states are a crictical a factor in deciding when to turn.. when to run. If you are light (and hopefully you've only got the 2 inboard 20's on board) on gas you are very nimble.. and can surprise your adversary. Be agressive.. but be smart.
Hope this helps!
Hang