Want to start a martial art! here is my advice for fisrt timers!  

Number one rule, like other sports warm up, second , martial arts have something that nearly all sports lack in some way and thats discipline!

you wont be able to kick as high as your master after the first session, get back to reality as soon as possible and don't overtrain yourself to be able to do that! flexibility needs time! Doing dynamic exercises will greatly help you, 3 months is all you need to attained max flexibility and to be able to kick cold! yes no warm up needed to kick that high! but it will be 3 month in hell, i guarantee it and i guarantee the results too! make a search on these exercises on the net. Also dont be shy during training! it happens often but you have to get rid of this shy attitude as soon as you start training!

after a year of training you'll see the real results of you'll never notice that you have progress this much in so less time

As for me i'm one year in advance in tae kwon do , thats right at the age of 25 or 26 i cant get my first dan!