i recommend going with flash/ignite. reason for flash over ghost is when people see Darius top lane there most likley always going to give him a hard time with triple gank's from jungle and mid lane. Flash would be a easier exit for darius. i Also recommend ignite for 2 reasons. 1 if u need that really fast last hit. and 2 it combos with your hemorrhage. so you go E auto W Q R F ..almost always a instant kill top lane from the bleed out and ignite.

ill only say 2 things about this. 1 always level Q and then E for easier harass. grab the player in, auto hit run back and hit with the tip of your Q for bigger dmg. and depending on you if your out of lane faster maybe lvl your W more than your E.