I took the TEAS two semesters ago to get into the nursing pgrm... and I did very well.
I suggest focusing on the material from ATI. I purchased the teas practice book on ebay http://www.atitesting.com/ati_store/...aspx?zpid=1175
and it was very helpful in that I was able to see what type of material would be on the test. However since I am a master at procrastination, and the book happen to of had all the answers written in it from the previous owner I didn't go through it very thoroughly. However what helped me the most was paying the $35 to log onto the ATI website and take a practice TEAS test. I took it the night before the test to get some of my pre-test jitters out of the way and it was most definitely worth every dollar, if not more. I can't recall what my exact test score was, but I do know that I was ranked in the 98th percentile.
ATI can be a cruel mistress... many nursing programs are using ATI material in addition to their required text etc... so it adds to the copious amounts of reading that is already required, but that extra reading is worth its weight in gold when it comes to ATI exams, the TEAS etc. They really set you up for success.
Hope this helps... Good Luck on you test!!