Use the game audits to check ball times and EB earned before and after the changes. Earnings and ball times should go a long way in helping determine if opening outlanes or lightening flippers or tighter tilts discourage players. In general, I set up games middle of the road on outlanes, never changed flipper bats, and only tightened tilts during tourneys. (Of course tourney settings in software if available, and also no ball save in tourneys, if possible).
I think ball save, tilts, no extra balls and outlanes are the most easily changed, and are standard tourney adjustments for most big and small tourneys. But, these also hurt my earnings the most, if left in that configuration (I kept a close eye on before/after, and gave thought to whether traffic or parties may have skewed the audits beyond settings changes).
p.s. this was a family fun center, so most players were kids/novices