How to get the best out of my striker (Costa/Lukaku)

[st4rt_]

I'm currently running this tactic atm and it's working rather well with just the one loss in 22 league games so far. Only running individual instructions on Cesc and that's just to pass it shorter and roam. He's been great. (Had previous success on an old Barca with him/this)

I've tried putting both Costa and Lukaku in each role and they're rarely scoring, any ideas for what I can do to improve the tactic as a whole and to benefit the lone striker?

Thank yas.