when you get a trick, or almost get it, try to break down exactly what you do, and remember it for the next time, then when you do em again, remember what 'points' you had to look for and run through em as a little checklist, you'll be back where you left off in no time !
i've been pretty much into gym practice(trampolines and stuff) and doing it like this helps me to pick up where i was during the last session, anyways, don't get discouraged, everyone has good and bad days :)