List off the biggest mistakes new ball python owners make?

[Bogertophis]

... What matters more is the source and health of the rats and what they have been fed. This is true for live especially, but also F/T.

That right there. You want to buy from reputable sources that feed their rodents properly- not on "junk food". The old saying "you are what you eat" applies to animals too.

And there are plenty of people that argue for one or the other (rats or mice) as being the "best nutrition", but they're very close in nutritional values when scientific studies have been done, so don't lose sleep over that.

The REAL reason rats are preferred for BPs is that when your snake gets larger, the appropriate "meal" size would be one small rat* or 2 adult mice, so which one do you think is more efficient & easier to provide? The single item (rat of correct size) of course! (Note: some snakes will only eat one item per meal, no matter what size it is. They instinctively get stressed & feel the need to hide after eating, as they would in the wild, where other predators are after them too & they're "exposed" when busy swallowing a meal.)

*A very large adult female BP might take up to a medium rat, but don't go above that size- & keep in mind that male BPs don't get as large as females, & if overfed, tend to go on fasts, which is a real pain (you'll keep wasting food, offering when they won't eat).