flexibility is something i excel at, here is how i got there.
Stretch before warmup after warmup and after workout. It prevents injury. Take your time in your stretches, it is important to breathe.
Equally important as breathing you must RELAX, stretching should be the calm before the storm, if you have to listen to whales humping or some crap do it.
Yoga works for some people, they have a great series of back stretches, but other then that i don't touch it. Think of this it is an entire art that has kept people in some sort of shape for a long time simply by stretching, so there has to be something to it. Try not to think about the fact your doing some tree hugging garbage.
Stretch every area of your body, from your ankles to your neck, including your wrists. One of the key factors of your flexibility is the muscle above and below the one which is being used for the stretch.
It only takes 10 min to do a really good set of stretches, if your doing it 3 times a day cut the length of the stretches in half to 5 min sets each.
It took about 6 months and i can touch my nose to my knee and nearly do the splits. I can snap kick someones head without leaning back.
There are no bad students, only bad teachers... until you teach at an inner city school.