Exchanging cards with a special someone on Valentine's Day (14 February) is traditional, whether you are already in a relationship or looking to start one. You can use a card to affirm your love for someone or to let someone know you're interested, anonymously or otherwise. When writing and signing your Valentine's card, make it original and unique to both you and the person you're writing it for -- you can then choose to leave your name or let the recipient try and guess your identity.
Choose a card that matches the personality and tastes of the person it's for. A wide variety of cards are available each year, from the loving and profound to jokey and flippant, and you need to pick the right one. If you're of a creative and artistic nature, you might want to consider making your own.
Write something original. Avoid resorting to overused cliches and sentiments (there are enough of these around every Valentine's Day). Instead, write something tailored to the person you're writing it for. If they have a good sense of humour, make it witty. If they have a very romanticised and idealistic view of love, make it profound and moving.
Write something memorable. This is your chance to win the love of a potential partner or retain the affection of an existing one. Put time, effort and thought into your message and make sure it's something the recipient will remember in the future. Flattery is always a good starting point, though don't go overboard.
Include a suitable send off at the end of the message. This could be "Love from," "Love always," "Fondly" or any other choice of words that you feel is appropriate. The right words depend on the state of the relationship, the stage you're at with the person in question and the feelings you are trying to express. Consider the feelings of the recipient; for example, you don't want to be too effusive if you aren't sure that your feelings will be returned.
Sign your name or leave it anonymous. There are no fixed rules about whether or not you should sign your name. You might find it easier to admit you like someone in a card rather than face-to-face, but leaving a question mark is a more mysterious and traditional sign off. Consider the likelihood of the recipient guessing that you're the secret admirer, because there's little point in leaving the message anonymous if it means nothing will ever come of your efforts.