Things that helped me were wrming up first jogging on teh spot bike riding and starjumps, are all good.
A flexable mid section and hips helps heaps, more than you would expect.
my routine was :
butterfly stretch, ie soles of feet together, focus on getting teh knees on eth ground then moving the feet towards the groin, then work on leaning all teh way over on your legs..pulling your feet in with your hands and leaning on your legs / /kneed with your elbows helps.
next i would do hammy stretches, one leg out at 45deg, other foot in at groin lean into leg, also extend back arm over head towards extended toes. helps stretch you obliques, if you can touch your toes or feel flexable, try sitting on your other foot, rather than just having it bent in,
stretch your ass....oneleg strait, place other foot, beside thigh, across leg, knee up to chestpullplave opposite elbow on outside of knee andstretch,
or
lye on back bring kneed up to chest and push across your body, hips flat so that you feel your outer gluts stretching
for quads
standing and pull foot up behind you, lying on stomach and do a pushup keeping hips flat aginst grounds, yiu will feel it in your hip flexors, if you bend your knees, foot to ass, it is even better!!
hips
sit leg in front bent slightly and lean into them focusing on a bending at teh hips, you will feel it in your lower hip area not your back, if in your back you are arching up too much
do a kind of lung, back leg knee, and shin on the ground, other leg on foot in front, keep pushing the front leg forward, (ensure the foot is further forward than your knee) this will work those quads well, and hammy on front leg, eventually you will get a front back split..
I used to sit infront of the tv legs as far apart as they would go, relaxed, lean forward into it 10 seconds stretch and 5 seconds rest, pushing the legs further apart each time. remember to relaxe them and shake them around so they get some fresh blood..
I would sit on the floor doing my uni work stretching for a side split for hours at a time..
another good one for you abductors, is sitting like a hammy strecth, omne leg bent towards your groin, lean forward, other leg strait out sideways, now sit up strait, as you get more flexable lean toward theoes of theutstretched leg, firstly focus on getting your ass on teh ground then leaning sideways,. this is a good oblique stretch aswell.
I could do front back and full side splits, I could actually place my feet on besser bricks and still have my ass on the ground. Or sit up legs strait out in front , while leaning forward I could swing my legs right around throuh a split, to them being behind me, and me lying on my stomach,, can also still have sole touching in shoes, feet into groing knees on ground,
another excellant hammy stretch is to stand against a wall, and have someone pick upyour leg and push it into your chest.
as a guide, from ankle to ankle during a split, is about the same, and ankle to wrist when hand is held above your head, that is how hight you can potentially kick..
High kicks are pretty flashy, and fun to do, but if going really high like that you loose power, and it can get telegraphic, Short asses like me dont have a lot of choice but, lol, If you want to kick high, then get a bag and kick it as high as you can, to build up power and speed, at those heights the muscles are way out of their comfort zone
When stretching holding for 10 seconds will do squat, 20 secs will maintain, 30 seconds will start to improve, this is daily.... I would recomened doing each stretch 3-5 times, pushing further into it each time...