I assume that Xen’s link is solid (as always), but let me add this:
If you’re a young guy (<21), you can increase your flexibility with just about anything without worrying too much- In fact, I can recall so many weird anecdotes from when I did Tae Kwon Do, where a lot of guys did insane things to be able to do splits as quick as possible.
It’s probably better to focus a lot on flexibility for a month or two, and then be able just to maintain it with one or two light sessions per week.
The older you get, the more complicated stretching becomes if you have less training time, aquired bad movement patterns as well as injuries nad imbalances.
Could you tell us about your specific aims, please?
I’m 19 and as unflexible as they come. Main goal is to increase lower body flexibility so I can squat and deadlift without injurying my back, my pelvic tilts forward as I get lower. I assume this is from tight hamstrings, hip extensors, and flexors?
From what I gather from that link, it is ok to do dynamic flexibility drills without doing a steady state cardio warm up?
Can I stretch anytime during the day without injury? How did you guys get flexible?