YOGA! Especially cat and cow poses! Also, watch your posture during tests and avoid slumping. http://www.chopra.com/articles/6-yoga-poses-to-help-relieve-neck-pain#sm.00001elxi6fm78cyjutbf51o0k8ar
Coffee is getting a bad rap over here. So, just to even the playing field, this: http://www.healthline.com/nutrition/top-13-evidence-based-health-benefits-of-coffee#section12
I think it depends on what kind of mistake it is. This post on Law School Expert Blog might be helpful to you: http://www.lawschoolexpert.com/comments-errors/
I believe it first appeared in PT57. Here is the list by PowerScore up until 2016: http://www.powerscore.com/gamesbible/logic-games-rule-substitution/index.cfm
(June 2009 LSAT = PT57)