Salam Neely,
Even though "please" definitely means لو سمحت and من فضلك but it also
means something else in Arabic.
1. Let's say you are asking someone to save you in a critical condition,
in this case "please" means َأرجوك for a male, and أرجوكِ for a female.
2. In case you are using "please" as a polite gesture when asking for
something, like in a restaurant for example and you want someone to
pass the salt for you, "please" here would be different , and it means:
"من فضلَك" for a male and "من فضلِك" for a female. Or you could use
"لو سمحت" for a male and "لو سمحتِ" for a female.
So it really depends on the context :)