Choose another ship. Ambassador is inferior to too many other cruisers in too many ways.
As for your skills? Ditch inertial dampeners completely. Also lose 3 points in impulse thrusters. You can also drop to 7 on all subsystem performance skills, since they only give one more point than at 9. Boost power insulators up to 6, put at least 6 points into armor reinforcements (unless you like dying to torps), and if you intend on being a tank, put points into threat control.