I would say at least 3% of your bankroll or about $750 a play. $250-$500 max a play seems too low. If you start off cold I could see downsizing to 1% of your roll for a while, but it would frustrating to be wagering just 1% if you are hot. Keep in mind this quote "Play long enough the house takes you. Unless when that perfect hand comes, you beg Big- Then you take the House."