Try memorizing it in chunks.. what i did was i memorized
bsi scene safe moi/noi # of patients ALS c-spine. theres one chunk
general impression avpu life threats airway breathing circulation transport theres your next chunk
after that its easy. OPQRST SAMPLE Vitals treatments and determining how often to reassess.
A few tricks for the medical- they will never give you a scenario that requires you to hold c-spine, however, you must mention the fact that you do not see the need for c-spine, otherwise they wont know that you even considered it. Also, they will not give you a scenario in which you have time to "stay and play." Always rapid transport.
Another thing I did to practice was I took notecards and wrote each step on it on the front, and then on the back i put what i would do during that step. I would then mix up all the cards and put them in order.
If you are affiliated with a department already, have some people give you scenarios, and have them follow the sheet. If you are not part of a department, have a family member or a friend help you.