ideally....
subsoiler, N-S then E-W
plow, N-S, then E-W
disc, N-S, then E-W
rototill,N-S ,then E-W
'old hay field' probably was 'no-tilled', maybe for decades,so ground is very compacted. You need to 'loosen it up'. Subsoiler gets DOWN to let water and air down to start to break it up,plowing turns it over, breaking it down better,disc and till make it even better.
If you just have tandem discs, add lots of weight,go N-S, then E-W, then increase angle of the discs.The 'art' of discing is knowing how wet the soil is and letting Mother Nature help you. If too wet, wait a day or two. Also drag a heavy beam, old chains, fencing behind the discs to help knock down, breakup the clods,level the field. It takes time and patience to restore a field,as well as a LOT of 'compost' !