The first step is relatively easy. Put a two slices of Toast in an envelope with the female's name on it.
Step two requires patience; requiring a 48 hour period of zero contact until the female gives back the envelope. Do not open the envelope again until you're in a secure environment.
If step two was performed successfully, the envelope should now contain nude pics of your target.
Step three requires speaking to her alone using a secret code:
If you ask: "Is the peanut butter in the potato?" and she answers with: "No it is in the apple sauce.", then the Toast/Envelope Method was performed successfully and you can continue your courtship on your own terms.
Alternatively, if you are kicked in the testicles upon uttering the code, it is safe to say she is not interested.