Do you dislike someone in your life? Do you suffer from low self-esteem? Such feelings can be corrosive to your well-being. A way to heal yourself of these negative emotions, and to boost positive feelings and self-esteem, is to practice Mettā meditation.
Mettā (loving-kindness, or benevolence) meditation is the practice of focusing on different people in one's life, and wishing positive things for them. Early Buddhist writings discuss the radiation of "mettā" to beings there may be in different spiritual "directions,"  for example, an early text writes:
One abides, having suffused with a mind of benevolence,
One direction of the world,
Likewise the second, likewise the third, likewise the fourth,
And so above, below, around, and
Everywhere, and to all as to himself;
One abides suffusing the entire universe with benevolence,
With a mind grown great, lofty, boundless, and
Free from enmity and ill will. 
An approach is to pass through stages of meditation during which one progressively cultivates benevolence towards any or all of the following beings in one's life:
(3) Neutral People
(5) Popular Figures (Such as Celebrities, Senators and Presidents)
(6) Sentient Creatures (Such as Pets and Wildlife)
The traditional meditation takes the basic form of wishing that a being in one's focus be free from animosity, oppression, and trouble:
May I bear no ill will, and be not corrupt in the resolves of my heart.
May these beings be free from animosity
May these beings be free from oppression.
May these beings be free from trouble.
May I look after myself with ease. 
A study done at Stanford University found that Mettā meditation can potentially increase feelings of social connectedness. 
Researchers at the University of North Carolina Chapel Hill have found that Mettā meditation can help increase one's sense of self-esteem, well-being, and positive emotions, which can stimulate the kind of benefits that come from experiencing positive emotion. 
How to Do Mettā Meditation
The following steps provide a guide about how to practice a Mettā-type meditation (note that this guide deviates from the orthodox Buddhist practice). First, find a quiet place and time in your daily life. Follow these steps (feel free to modify them however you like):
(1) Close your eyes if you feel comfortable doing so.
(2) Breath in through your nose and out through your mouth several times until you feel more relaxed.
(3) Keep breathing as above, and try to empty your mind.
(4) If thoughts pop into your head, just notice them, and then let them go.
(5) When you feel more focused, try to imagine the face of someone in your life.
(6) Try to imagine them as a whole: who they are, where they are, the sound of their voice, how you feel about them.
(7) Say to yourself, or out loud, the following words about them:
May [someone] be healthy.
May [someone] be happy.
May [someone] be free from harm.
(8) As you say these words, imagine that you are radiating these feelings toward to them, wherever they may be.
(9) Now try to empty your mind again.
(10) If thoughts pop into your head, just notice them, and then let them go.
(11) Choose a different person in your life, and repeat the steps starting at (5)
(12) Finally, focus on yourself.
(13) Imagine yourself as a whole, and notice the things that you like or dislike about yourself, letting them go.
(14) Imagine yourself as a child, and notice something that you remember that you wanted when you were little and never received.
(15) Imagine your current self giving that thing to yourself as a child.
(16) Now say the words, focusing on yourself, as in (7).
(17) Focus on your breath, and when you feel ready, open your eyes.
2. "Vatthupama Sutta: The Simile of the Cloth," http://www.accesstoinsight.org/tipitaka/mn/mn.007.nypo.html
3. "Cunda Kammaraputta Sutta: To Cunda the Silversmith," http://www.accesstoinsight.org/tipitaka/an/an10/an10.176.than.html
4. "Loving-Kindness Meditation Increases Social Connectedness," http://spl.stanford.edu/pdfs/Hutcherson_08_2.pdf
5. "Happiness Unpacked: Positive Emotions Increase Life," http://www.ncbi.nlm.nih.gov/pubmed/19485613