When I did my LPI-1 I started by doing this two tests to see where I'm at:
And after that went the IBM road. I'm really gratefull to the guys/gals who wrote them. Might not be up2date but are just the right size with the right depth in the right warm wet place, aehm.
I also checkeout some of the books on the market but refrained cause I did not had the money then. Maybe check your library. Any book about Linux is good. Specialy when you start out.
Generel more stuff is here: http://www.lpi.org/exam-preparation/self-study
Check the page here http://wiki.lpi.org/wiki/LPIC-1_Objectives
and see the man pages of the commands involved.
And not to forget if you want your feet wet the http://slackbook.org/