What positive percentage should I sell at in order to make a profit and avoid transaction fees?

Hi, I’m really new to the whole world of crypto and digital currency and as google wasn’t providing me with a straight answer i’ve decided to retreat to the most factually accurate place on the internet, reddit. My biggest question at the moment revolves around transaction fees, specially withdrawal fees, what percentage of profits is lost in a simple withdrawal of 100% of funds out of any currency? Any additional information that you would have found useful when you were in my position would be greatly appreciated!! :))