Hi Doodle
I play a lot of live cash and a lot online.
profit loss, is one consideration, bankroll is another, the type of player you are also counts for a buy in.
But what never changes about your buy in is this.....The size of the blinds.
What shouldnt change about your game is the way you play, position, patience, reading the plays and players..
I was asked this same question just last week during a live game in which I bought in with the maximum (like I always do). My reply was, I can lay down big hands, I can lay down AK AQ on flops that I dont hit, I can lay down hands where I know people hits rags after seeing the flop after being priced through pot odds.
So, I will ask you to ask yourself this question, am I disciplined? If the answer is yes and you can lay down the big ones and avoid the sucker flop odds bet, then you should buy in for the max.
If the answer is no, protect your bankroll, buy in minimum and hope you get lucky early.
Steve