Strike price selection for sold puts.

Most people overthink this completely.
Here is what I do.
I only sell puts on things I already feel are undervalued.
Then I go 10% below the current price.
Q at $600?
I sell the $540 put.
I am already buying something cheap. (assuming this in the example)
Then I am going 10% below that.
The market has to fall 10% from an already undervalued level to put me in assignment range on expiration date.
& guess what, I always have my ratios in check to be able to take assignment no mayor what!
I will be happy to get paid to buy shares cheaper in the future and not having the cash frag of cash secured puts.
The portfolio secured put wins again.
Simple. Repeatable. Works.