Who is you're favorite female porn star?
Mistaking "you're" for "your" - or vice versa - is a common writing error most people have made at least once. It is also a grammatical mistake that can be disproportionately irritating and confusing for the reader. Fortunately, once you know how to differentiate the two, you'll hardly ever mix them up ever again.
First, understand the proper usage of the word you need. The best way to do that is to sound it out. There is a replacement test that will tell you for certain which word will fit. Read the sentence with 'you are' in place of where the 'your/you're' is intended. If it makes sense, then 'you're' would be right. If not, then 'your' would fit.
You could also replace your with 'my' in the sentence. If it fits, then use 'your'.
Hope this helps. You'll thank me one day.
[P.s. Louise Willy.]