hmmm well theres loads of ways to do them and you will pickup your own styles later on as you get better at them... try center yourself over the board when going for the ARS and keep yourself right up, so dont drag those knees when you are about to launch it... follow into the rollspin off a clean section and timing and the section you hit is pretty important... then even if you get it half done and land in the flats it doesnt matter if it takes the time till you are on the beach to come out the spin cause its still completed.. then just work on rating faster and faster.. also maybe ask someone in the water who knows how to do them if they see you attempt and ask them what they might be thinking you can be doing wrong...
or try the following from the legend himself...
http://www.mikestewart.com/
click on Methods and then scroll across to ARS and click on it.. it will load with some help
Good luck bru