None vs Empty String in Python

if variable and variable.upper() == 'X'

is a little less wordy. It will also treat None and the empty string in the same way if that is something you want

Edit: Note that this does have different semantics to the expression you posted in the way it handles empty strings... i.e. in your expression the rhs of the and would get evaluated if variable is the empty string, but in this expression it would not as the empty string evaluates to False

You could cut down on code slightly by just writing

if variable and variable.upper() == "X":
    #Do something

If the variable is none or empty, then it's equivalent to False.