“Laima’s themes are love, unity, blessing, luck, destiny and magic. Her symbols are wreaths and swans. The Lithuanian Goddess of fate, luck, beauty and magic swoops into our lives in the form of a swan (* please see “UPDATE”) reminding us of the transformative power of love. Traditionally, all Laima needs to change from one from to another is a swan feather, alluding to Her nature as a shape-shifter who uses magical charms to manifest Her will.
Around this time of year, young people in Lithuania gather in a temple at sunset, then go into the forest to harvest summer flowers. From these, circlets and strings are made to crown and bind lovers together in Laima’s and nature’s beauty. Then the young people dance to together round a birch tree (rather like a Maypole) singing to the Goddess and asking for Her blessing. This is a lovely tradition that can be adopted by gathering summer flowers and holding hands around them at your family supper table. Allow Laima to renew your love and unity in a moment of silence before dinner. If you live alone, invite a close friend to join you instead.
Also, find a small rose-vine wreath at a craft shop. Adhere the image of a swan to this somehow (representing Laima), and hand it where you can easilty see the wreath regularlily. Each time you do, remind yourself that love is the most pwerful of all the Goddess’s magic – and that includes loving yourself.”
(Patricia Telesco, “365 Goddess: a daily guide to the magic and inspiration of the goddess”.)
Patricia Monaghan tells us that this “Baltic Goddess of fate sometimes appears as three [with Her sisters Kārta and Dēkla] or seven Goddesses to symbolize the many fates possible. Laima, like the Norns and Fates, measures the length and happiness of a person’s life. Sometimes called Laima-Dalia, ‘happy fate’, She was invoked in prayers: ‘Oh, Laima, thou art healthy; give me thy health.’ Often mentioned in the same prayer was the sun Goddess Saule, for Laima measured the length of the sun’s day as well as a woman’s life. Laima was Her name in Latvia; She was Laime in in Lithuania; in both countries She was sometimes pictured as a swan maiden (* please see “UPDATE”) or as a multiple Goddess” (p. 189).
“Laima…[is] generally associated with the linden tree. Together with Dievs, the sky, and Saule, the sun, Laima determines the length and fortune of human life. In the course of each life She helps arrange marriages, oversees weddings, protects pregnant women, and appears at childbirth to pronounce each infant’s destiny.
Revered as patroness of cows and horses, Laima decides the life span of plants and animals and determines the length of the day.” 
I did come across one piece of conflicting information. Monaghan states that “Laima was Her name in Latvia; She was Laime in Lithuania” (p. 189). Wikipedia states that “In the Lithuanian mythology, Laima (fate, destiny) is often confused with Laimė (good fortune) and Laumė (fairy). Other related deities include Dalia (fate) and Giltinė (The Reaper).”  However, Encyclopedia Britannica states that “Laima, also called Laima-dalia, (from Lithuanian laimė, ‘happiness,’ ‘luck’)” .
* UPDATE (06/25/2013):
A very knowledgeable native Latvian lady I exchanged emails with shared some wonderful information with me that contradicted what Patricia Telesco and Patricia Monaghan wrote concerning Laima’s association with swans. She stated that Laima is “connected to a cockoo, a black or white chicken or a black or blue snake, but never with a swan.” She also stated that “Laima appears with a green linden or birch sauna besom like this:
Also, the information found in the Wikipedia is very accurate: “The most important goddess of fate is Laima (luck). She lives on Earth and is closely involved in human life. Her basic function is related to birth of child and deciding its fate. Traditionally women would give birth in bathhouse. The path to it would be cleaned so Laima could easily make her way to help in the birthing process. The woman would be ritually cleansed and would offer prayers and give ritual offerings to Laima. After successful birth married women would feast, with Laima being reserved a place of honour, in the bathhouse as sign of gratitude. She would also determine persons fate – a decision even she herself could not alter afterwards. She was expected to help in other important aspects of life as well and cared for well being of the people in general. Unmarried girls would pray to her to give them good husbands and happy marriage. She also ensured fertility of fields and animals (horses in particular) to some extent. Another two goddesses with similar function are Kārta and Dēkla. Goddess Māra also has several functions in common with Laima. Although this view has been criticized, many researchers agree that Māra is synonymous with Saint Mary. It has been suggested that Mary took over some functions of earlier deities, including Laima. However, Māra was used to refer to Saint Mary, who was also called upon during childbirth and to help with number of ailments by either her modern Latvian name Marija or number of Christian euphemisms. All these were also used as euphemisms to refer to uterus in folk magic. The opposing view, based on comparative linguistics linking her with wide range of other Indoeuropean deities, is that she was important pre-Christian chthonic deity that both gives and takes life.” 
Britannica Online Encyclopedia, “Laima“.
Monaghan, Patricia. The New Book of Goddesses and Heroines, “Laima”.
Wikipedia, “Latvian Mythology: Fate goddesses“.
Bookrags.com, “Laima Research and Articles“.
Covenantofrhiannon.org, “Ancient Lithuanian Mythology and Religion“.
Latvianstuff.com, “Latvian Earth and Water Deities“.
Mallory, J.P. & Douglas Q. Adams. Encyclopedia of Indo-European Culture, “Fortune Goddesses” (p. 212).
Motz, Lotte. The Faces of the Goddess, “Laima: Goddess of Birth and Fate” (p. 80 – 83).
Ortega, Pedro. Heresy and Beauty, “Lithuanian Goddess“.
Wikipedia, “Latvian Mythology“.