Have you noticed how mystical our culture's talk of love is today? Whether it's the girl whimsically longing to "find true love" (as if it is some magical creature evading her grasp), the boy in reluctant surprise who admits that he "might be in love" (as if it were a disease which has crept up on him), or the couple which speaks of "falling in love" (as if it were a pit into which both stumbled during a blind, dumb stupor), there appears to be very little conscious understanding of what love actually is among most people.
Is vs. Does
Of course there are many who would claim to speak of what love is (typically the adult speaking to the adolescent, who "doesn't know what love is yet" -- as though love were some mystical knowledge imparted to you at a certain age). But these don't speak about what love is so much as they speak about what love does.
"Love waits", "Love puts the other person first", "Love makes you do crazy things", "Love doesn't give up". These are all great and true (in particular respects) descriptions of what love does, but they do very little to explain what love is. If you want proof, simply consider that one could do all of the things listed above (and all the things which could be listed about what love does), and still not have love (see 1 Cor. 13:3). If it is possible to fake love by performing supposedly 'loving' actions (and it is), then the actions, themselves, cannot be love.
Love is Value
If love is not actions, but the fuel for 'loving' actions, then love must be that which fuels action: value. Value is the invisible reality in the soul made visible through the actions of the body. Actions flow from values. Love, therefore, is the invisible reality in the soul (value) made visible through the loving actions of the body. To love someone is to value them. To value someone is to consider them of value to oneself. The greater the value, the greater the love.
True and False Love
Why then, do we speak of "true love" as though there is some sort of false love, if love is value? Either you value someone or you don't. Either you love someone or you don't. Is there true and false value? In a manner of speaking, yes. To be more clear, there is rational and irrational value. It is possible to have irrational values, like valuing video-games over productive work. Likewise, it is possible to have irrational love, like 'loving' someone who is truly destructive to you and your life. Both are instances of mistaken value; instances of mistakenly believing that something or someone is of value to you when, in reality, both are ultimately destructive to you and to your life.
How does one avoid such errors? The solution is the same in both cases: one must properly discover and identify that which is objectively valuable to one's self and one's life. The solution to valuing video-games more than productive work is to discover and genuinely be convinced of the superior value in productive work; to see the glory of real life achievements as superior to the childsplay of conquering make-believe foes; to feel the triumph of a success wrought by maximizing and exhausting the creative capacities of one's entire being (mind, soul, and body) in the physical world. The only effective weapon against irrational value is the discovery and embrace of rational values.
Likewise with love. Rational (i.e. "True") love is the recognition of rational values in the person and character of another. The greater those values, the greater the love. Irrational (i.e. "False" or "Tainted") love is either not truly love at all, or love which primarily values the irrational in another person.
There are two variants of irrational or 'tainted' love -- and these two impostors of true love are the reason for much disillusionment about love in our culture today. The first is not really love at all, but the pretense at love; the illusion of it. In this false love, it is not truly the other person who one values, but the false sense of security and value which one gets from "being in a relationship" with that person. A schoolgirl may claim to be in love with the most popular boy in school, when in reality what she truly loves is the illusion of how valuable she would seem to be if she really were in love with (and loved by) him in the true sense. She desires the effect (feeling valuable) without the cause (having worthy values which would make her relationally valuable). The root of this false love is often insecurity about oneself, manifested in a desperation which attempts to overcompensate for the feeling of a lack of personal value. It is not so much that this person values irrationally, but that he (or she) has not discovered how to hold deep, personal values at all; he mistakenly thinks that he will gain value by being appraised as valuable by someone else, rather than realizing that the appraisal of others is only as valuable as its accuracy in that which it is appraising: one's own personal values.
The other type of 'tainted', or false, love is that kind which primarily values the irrational in another person. This can more appropriately be called "love" (more-so than the previous type of tainted love), in that it truly is a valuing of the other person because of what one sees as valuable in them, but it is a twisted sort of love because it will only result in the ruin of both the lover and the beloved. To value the irrational in another person is to ultimately value the destruction of that person -- whether one consciously intends it or not. True love values that which is most objectively valuable in the other person.
How To Love
"To say 'I love you' one must first know how to say the 'I'". -Ayn Rand
If true love is valuing that which is most objectively valuable in another person, than there seems to be some preliminary requirements for one to experience true love: the ability to value, and the ability to identify and value that which is objectively valuable.
"The ability to value? Doesn't everyone have that?" In the most surface-level sense, yes. However, what is meant here is the ability to hold deep and unchanging values, by oneself. One of the problems in our culture today is that many people are incapable of any sort of value which is not transient and fickle, or which is not simply a 'following of the herd'. Apart from holding firm and resolute values in one's own soul (regardless of what others may think), it is impossible to value anything of significance in another person -- and it is impossible for any other person to value anything of significance in you! So, in order to rediscover love, we must rediscover the weight and glory of deep, lasting, personal values (i.e. rational egoism)
The next step is the ability to identify and value that which is most objectively valuable. This means discerning (appraising) the objective value of everything in life. If you are not able to figure out that which is most objectively valuable (and why), then you will not be able to identify the objectively valuable in another; and if you attempt to love another person apart from identifying and valuing that which is most valuable in them, then you will likely wind up valuing (and thereby encouraging) that which is less valuable in them -- leading to their destruction. Therefore, to truly love another person, you must learn to identify that which is truly lovely in them; which means you must learn to identify that which is truly lovely (i.e. valuable), in general; which means you must discover an objective standard and hierarchy of value (i.e. you must think philosophically about value).
So, how to love? You (your self -- your ego) must value (for yourself; find valuable to you) that which is objectively valuable in another person. In other words, to love, you must be a rational egoist.