The student pilot reported he was on a solo cross-country flight. The airport runway conditions were reported as good, braking deceleration and directional control was normal. As the airplane crossed over the approach end of the runway, the pilot felt he needed to lose a little more airspeed and held a flare a little longer and landed further down the runway. Upon touchdown the airplane began to slide to the left of centerline. The pilot attempted a go-around maneuver by adding power. The pilot was unable to correct back to centerline, which resulted in a runway excursion. The airplane impacted taxiway signs and lights sustaining substantial damage to the left wing. The pilot reported that there were no pre-accident mechanical malfunctions or failures with the airplane that would have precluded normal operation.