Collateralize your downpayment & secure fair price

Just finished a call with another self funded searcher who is about to purchase a door manufacturer company. Two ratios to ALWAYS look:

Downpayment to free cashflow (for profitability) (20%)
Downpayment to net worth (to collateralize your worst case scenario). (At least equal).

Which other ratios do you look at for a very quick review of a deal?