Use HQ mats and try to find a rotation where you can spam Great Strides and Standard Touch as many times as you possibly can before you finish off the synth with Standard Synthesis/Basic Synthesis. You will likely also want to keep up Steady Hand to prevent yourself from wasting attempts. Since Great Strides only triggers after using Standard Touch and you have 3 times to use it you can prioritise it first followed by Steady Hand then either Standard Touch right away or use Waste Not then Standard Touch, depending on whether you can get more moves in for Great Strides/Standard Touch before running out of GP or attempts. Also for a bonus make sure you shove in plenty of Perception/GP materia into your gear.