Timing is Everything: Unlike pregnancy tests, which are best used with "first morning urine," OPKs are usually more accurate if used between 10:00 AM and 8:00 PM, when LH levels are highest.
Consistency: Test at roughly the same time every day starting a few days before you expect to ovulate.
The Result: * Positive: The test line is as dark as, or darker than, the control line. This means ovulation is likely imminent.
Negative: Only the control line appears, or the test line is faint.