earnest money in an option contract

I am new to wholesailing and trying to learn the ropes before I dive in, my question is how much is reasonable earnest money for an option to buy contract? I have heard as low as $10 and as high as 5% of purchase price. Does anyone out there use a certain amount and has anyone had better success using more money and maybe the pros and cons of each. Sorry if its alot of questions but I enjoy hearing from people that are out there doing this each and every day.