I highly recomend you to start betting with your first 5k satoshis!
There is no difference at all in the chance of winning.( i would still rather bet small amounts slowly then get my profit safely) Always remember that when we do talk about safe betting it is about the amount that you will be losing.
How many should I bet?
I think it's safe to bet until you get a profit of 5% of your actual balance, it's too few profit, but you'll not risk too much and get a little everyday.
But you want to do it only ONE TIME A DAY! Don't think "oh, I'm getting btc so easily, lets do it again". Because if you do it a lot of times, you WILL LOSE.
Let's just say that you have a 1 btc capital then you bet them yet you haven't get the 5% profit should i not stop? that is insane
Anyways i should get to the point. what method that works on you does not work for us + that doens't work for you all the time either let's say you have earned 40% of your total capital yet lose 60% as well. That makes sense tho,