EDIT - ADDITIONAL TIP
For Takeoff,
ALWAYS ENSURE YOUR TAIL WHEEL IS STRAIGHT BEFORE COMMITTING TO TAKEOFF!
As you make your final turn on to the runway and come to a stop around the centreline, if possible, go to external and check the tailwheel. Chances are it's pointing the direction you just turned from! If you power up now, guess which way you're gonna be headed? That's right - into the grass!
As you get to the runway heading you should already be applying brake/rudder opposite to your turn in order to stop the a/c on the desired heading; the trick is not to stop dead once you've got her lined up but let the momentum carry you forward and roll a few yards/metres to ensure your tailwheel is pointing straight down the back of the tail.