My name is josh I'm new to this site but been printing for about 1.5 years. WHen i first started i had lots of trouble i was clueless to the steps needed to do a good print job. I felt like quitting so many time but kept going cuz i figured i spent so much money and time i cant quit. So i suggest you continue practicing if it doesnt work the first time take a break ease your mind and try again.
Now to answer your problem you said the tshirt moves and the registration gets messed up. First rule dont print with out adhesive the adhesive keeps the shirt from moving anywhere which means if you lift the press and noticed it doesnt have enuff ink you can bring the press back down and it should land on the same spot. If it is white you are printing on black i like to put one coat of ink, flash, let it cool for a couple sec. then another coat makes the print look real nice and thorough. you should have atleast a gap between the shirt and the screen about the size of a penny. KEEP ON TRYING DONT LET ANYONE OR ANYTHING DISCOURAGE YOU. 