"Blessed are the pure in heart, for they shall see God."
Purity is a priceless gem. Once lost, it can never be regained. Purity of both body and heart are very valuable. Since this series is on a lady's heart, I will focus here on the latter of the two.
Purity of the heart is extremely important. Yet it often goes unnoticed. Often, a girl doesn't realize her emotional purity is fading away until it is too late. Imagine somebody gives you a beautiful charm bracelet with ten shining charms. Each charm is a perfect sapphire, emerald, or ruby. Every time you flirt (consciously or unconsciously) with a guy, or every time you fancy yourself in love, one of the perfect jewel charms is given to that guy. What shame! When you marry, you would only be able to give your husband nine or five or none of those jewels!
"…So it is with Purity. God has given you a special gift (purity) and He wants you to treasure it. When you steal looks at the dashing man in your corner of life, you're starting to corrupt the gift He's given you. When you start giving parts of your heart away to other men, you're giving away your purity as well…"
So how can losing our purity be avoided? Clearly we are unable to protect it by ourselves alone. Ideally, a girl would give her father her heart*. He would guard it diligently and keep it until the right man comes along. Since he is older and consequently gained more wisdom over the years he will know much better than us who is the "right man".
"…Set standards for your future husband. Have in mind what character traits you'd want to see. Just because a guy's "cute" doesn't mean that he's a nice guy. Or he just might be a nice guy but he might not be considerate to authorities, etc. If you have in mind what you want, you won't be as likely to fall into a crush. Ask your dad to scope the guy out if he's asking to court you. Let your dad know what qualities you're looking for. Most importantly, ask God if he's the right man for you…"
"How can a young man keep his way pure? By keeping it according to Your word."
Other scriptures to read and consider would be Psalm 24:3-4, Psalm 73:1, Proverbs 20:11, Proverbs 22:11, Philippians 4:8, 1 Timothy 4:12, and Titus 2:5.
*I understand that not all girls are able to give their father their heart. Circumstances which separate the father and daughter, or the father being unwilling or unable to accept it would be sad. In such cases it is best for a girl to look to her mother or a mentor, and ultimately, as in everything, to God.
Note: All quotes in italics are taken from Pure Little Ladies Ministry's post What Is "Purity"?.