Definitely buy Next 10 (coming out in early-mid-May) or at least a few of the most recent tests. Personally, I started off like you, mid 150's w/o practice..after reading a couple of guides (mostly skimmed through them, because like I said...not all of their techniques are helpful), I did another preptest and got low 160s.(I'm talking about a time difference of 2 weeks). I'll more serious studying in early May (probably a test per day...cause I don't have to work)...and my goal is in the high 160s or hopefully even 170. Improvements could range from a few points to a lot like 10 points or more. It all depends on what you do to prepare. Of course, w/o sufficient practice, it'll be a dream to improve significantly. Getting the two books (actual and more 10 is a good start)...do you have explanations for them? It'll safe you a lot of time thinking why you missed certain questions. Hopefully next 10 will be out according to schedule (ie April 30th), or else buying individual tests will be more pricey.