Early morning practices are a wonderful experience of greeting the day with a deeper acceptance of one's self and awareness of a greater landscape of possibilities. As with starting any practice, I also see sun salutations (Surya Namaskar sequences) as offering a wide variety of opportunities. Some practitioners take a specific sequence, some count breaths, some add standing Asanas like Virabhadrasana I or II, (Warrior) or Trkonasana (Triangle), or variations of lunges and twists in Ajanyasana (knee-down lunge) or Utkatasana (chair/fierce pose). Are any of these "right" or "wrong" in a sun salutation? I believe it is only really important if you are practicing a specific style of yoga that requires repetitions of specific alignments through particular Asanas. In either situation - a set flow or with additions - Surya Namaskar is a gradual process that will change your sense of being as you go along.
Beginning a yoga practice starts with the breath, and waking up the awareness. There are so many ways to do this, and all of them are reminders to be fresh to the moment, not leaning on expectations or memories, not judging or causing pain. I teach variations of physical warm ups that draw attention to different parts of being. In my own practice I do much the same, whether I start by sitting or standing, or even flat out on the floor, slowly through Pratapana (warm ups) or jumping in to Vinyasa (Asana flow) like Surya Namaskar.
I take personal practice as a true exploration and believe that sequences are built through understanding of the breath and curiosity about the body as a vehicle for experience of Prana (life energy) and grace. Some mornings I will repeat a series of Asana in a flow many times, sometimes I hold each Asana for many breaths. It may include variations or be the classical sequence. I've read that Surya Namaskar is a fairly recent addition to the pantheon of yoga practices, and that the ancient yogis had no requirement for this particular series. It evolved as a wonderful integration of movements with the breath that serve to open energy channels throughout the body, generate inner heat, strengthen limbs and core, release joint tightness, offer an inversion, and bring the mind into a more devotional state. Whatever my practice, I am building upon who I am, and how I approach, observe and release my own reactiveness. I learn to hear the deeper impulses of energy and fear, and I gain integration of my body and mind to the point when I can sit (or stand, walk, or lay down) in a natural meditational state. The practice helps me open the spaces inside me that encourage a less judgmental way of life, a more generous heart, and even a better humor in the face of darkening clouds on the horizon or right in my face!
I think many people cut short this last meditational phase of personal practice -- seeking physical integration and moving quickly on to other daily tasks, as if the practice is a warm up for the day. In some very real ways, I think practice IS a warm up for the day. Just like the sun rising, the light begins with subtle aspects, gradually spreading and brightening, as more and more of the world around us comes into view, and absorbs the heat. A yoga practice is really the same, and even on a morning thick with clouds, I can still salute the sun, finding its light illuminates the shades of gray above me. So, too, does the sun salutation series open spaces in which to see more clearly which way the practice may lead. One day it could be shoulder openings, another into twists, or strengthening standing postures. Perhaps the breath is crying out for Kapalabhati (Skull Shining Breath) breathing in Setu Bandhasana (Bridge pose) or deeply meditative Nadi Shoduna (Alternate Nostril Breath) in Virasana (Hero's pose).
Attending classes can help with the internal absorption of sequences, and introduce a combination that effectively raises energy, strengthens, calms, or opens awareness of fears or healing effects. Yet again I think of the sun, only by rising does the sun light the world. You will only find your personal practice by taking time to see what turns up in it on any particular day. You can begin with following what you remember from classes, or working with a tape or DVD, but the sooner you can turn off the external directive voices and begin to work from that internal voice, the brighter and more illuminating your practice will be.