paul, in addition to chromes suggestions you might also consider the class of todays race compared with its last start,

often spot last start winners that get up again at juicy odds when rising sharply in class, but of course plenty of them also run nowhere

& regards 'best Average Prizemoney Per Start', i find this to be one filter that leads to plenty of losers in those horses rated highly (eg unitab 100) or short priced,

must be a lay method there somewhere...