In general, doing drills everyday is the key. Here are some ideas:
(1) The class handouts include math warmups for most of the sessions. Brief, but a nice way to dive in to each topic. Downloadable from our site.
(2) The "Easy" problem set in the Official Guide to the GRE revised General test (p. 145)
(3) The Foundations of Math Drills handout (though you may have already done this). Downloadable from our site.
(4)
http://www.purplemath.com/quizzes.htm . This is a list of math sources around the web. Of course, these aren't GRE specific, and you should ignore trigonometry, calculus, etc. (ignore anything beyond algebra and geometry)
(5)
http://www.algebrahelp.com. The worksheets of problems are not GRE specific, but they start at a fundamental level and have accompanying lessons and worksheets. It is free.
Good luck!