Properties vs. Parameters

I have a question for all of you programmers out there--a pretty basic question I'm sure.  It's a question that makes me wonder how I've managed not to figured this out yet after years of programming.
Say you have a class and the class has a function that returns a dataset.  If the function requires a few values to return data how do you determine whether you create parameters for the function or create private fields and get and set properties and just call the properties get functions?
Excuse my pseudo code please...
Properties option
private x as integer = 0
function getX()
return x
end function
function setX(xValue as integer)
x = xValue
end function
function getData() as dataset
...
getX()
...
return Data
end function
 
Parameter Option
function ge ...