The fundamental requirement for choosing circumcision is choice itself. I made that decision of my own free will; nobody made it for me, and it would be unacceptable as an adult for anyone to have tried. If you choose to be circumcised you must be sure that it was your decision. I don’t regret this choice, and neither would you, but be sure to make it yourself either way.
There is only one fundamental requirement for “Choosing Circumcision”, and that is choice itself. Circumcision is a choice I have made of my own free will. Nobody has tried to take away that decision by making it for me. I have made the choice to remove my foreskin myself.
It is my understanding that in some cases doctors will recommend circumcision for boys or men for medical conditions. Short of something like cancer of the foreskin, I think these recommendations are suspect at best and tragic at worst. If you have phimosis (tightness of the foreskin such that you cannot retract it, or erections are painful) circumcision may not be your best choice. Consider preputioplasty as another option on the table.
If you are a teen or grown man interested in circumcision, though, you have my implicit support for that decision, should you choose to make it.
Remember, circumcision is both personal and permanent. Choose wisely.