I would recommend to buy pacey AM L or R. I got good ones and they have best avr in team and lots of assists. Also I would suggest one striker that's good in the air. And try using target men - if opponents' DC's are weak in the air, target that striker and to head. Else, target wingman and run onto ball.
One more hint: you need someone with good set pieces. Those few more goals from free kicks/corners are worth it. And from penalties of course, you don't want them wasted

. My recommendation is Ciaran Donnelly, got him on free transfer (he's Scottish, I'm playing with Scottish leagues on so I don't know if you can get him playing England only) - AM R, incredibly fast, strong, good set pieces. Rest not so good, but for Conference he's great.