If ovulation strip shows smiley face, what does it means? Does it means I am ovulating and can conceive if have intercourse today? How accurate is the OPK?

Nobody can guarantee conception. You have to find out when your most fertile window is. Conception is likely to happen when your egg is fertilised 5 days leading up to the day of ovulation. The easiest and most fuss-free way is to have sex every two or three days. http://www.babycentre.co.uk/a1809/when-is-the-best-time-to-get-pregnant