Well I'm no expert (it's hard to be an expert on wisdom thousands of years old...

) but from my experience, some important points off the top of my head are...
Listen to your own body, every part.
Do not compare yourself with others...because yoga is not about achieving anything, not about achieving an ideal pose.
The very act of going into a pose correctly, comfortably and breathing deeply, no matter how inflexible your body is, is the most effective in healing your body, so comfort is key.
Correct breathing is one of the most important things in yoga, as in life...many ailments can be cured just from correct breathing.
Imperfection is beautiful...don't be hard on yourself if you can't do a pose and everyone else can.You're that much more fortunate because you can see the effects that much more!
I would recommend ashtanga yoga for beginners...very kind but powerfully healing and breath . (Personally, I would be wary of Bikram yoga...people pass out...not enough oxygen (fresh air/oxygen is crucial)...and he was involved in a courtcase trying to patent ancient, traditional poses as his own, suing others who taught them

...this to me is the epitome of what yoga is not...)
Yoga means "union"...union with your true self, with your own body, with God, with the universe, with nature, with friends and family...so just feeling that, being thankful in the feeling of oneness, helps your pracitce and life tremendously.
That's it for now, you can ask me anything you want.
