How much cash should I use for a down payment & holding costs

[Patrick Martone]

I cannot decide what percent of my cash to use as a downpayment, and how much to set aside for holding costs. 

I will be doing flips and have my credit line approved. I was thinking of using half of my cash as a downpayment, and the other half as a surplus to pay the holding costs. I'm sure I can go 70% downpayment and 30% surplus, but I want to play it safe.