The basic ingredients 

Bananas
Brown Sugar
Butter
Cinnamon
Rum
Banana Liquor

Generally the ratios are oriented around the number of bananas, and generally it's one banana per serving.

1 banana =
2 tbl brown sugar
1 tbl butter
dash of cinnamon
1/2 oz. banana liquor
1 oz. rum
1 large scoop vanilla ice cream

Melt the brown sugar over a low flame with the butter.  Make sure the sugar and butter are well mixed and add the banana.  Sauté until the banana is quite tender.  Dash on some cinnamon and then add the rum and liquor. Ignite!  Serve immediately over ice cream.

Here are a few tips.  Get the right size pan to bananas.  If there is too much space (i.e., you put one banana in a large pan) it won't ignite.  Although lighting it on fire is showy, it also burns off the alcohol and give a better taste.  

Use bananas that are not too ripe, otherwise they will practically disintegrate.  Of course, if they are not ripe enough, it tastes terrible.  I generally get ones that are firm, without mottling, only a touch of green at the stem.  Use large organic bananas.