The best book is one called "How to pass professional level psychometric tests" by Sam AL-Jajjoka (Jojjoka?). It is the SHL stuff that Qantas uses down to a tee. Others that I used, and I obtained all these through the library, are:
"How to master psyc tests" by Mark Parkinson
"Check you IQ" by Russell and Carter
"IQ testing" by Russell and Carter
"Further Mathematics" by GS Rehill and R McAuliffe (very good)
"Business maths for senior students"
"Maths for the real world" not sure of the authors of those two
"Psychometric testing" by Carter and Russell (no good)
I also bought "Mechanical Aptitude and Spatial Relation tests" by ARCO from Concept Aviation supplies at Bankstown (phone order). Qantas can fax you some examples and also go to SHLDirect.com. Have a look at the Qantas examples and the ones on the SHL website to get an idea before you get into the books. You'll save a lot of time. Don't get bogged down on what is the missing word type thing as they aren't relevant. In some of the IQ books there were only a few of any relevance. Steve Holding in Brisbane runs courses on the maths and spatial reasoning parts too. With the personality and motivational questionairres, be honest because if you aren't and put down what you think they want to hear that will be it for you.
With the skills test practice using a playstation or spend some money down at a pinball parlour.
Diet can also come into play. Exercise to get fitter as it makes you think more clearly. Go for a half hour jog on the morning of the test too as it stimulates a chemical in the brain. Chew gum during the test for the same reason. Coffee will make you more alert. Try having oily fish (canned salmon) for several weeks before the test each day and L Glutamin (available at health food stores) can increase your IQ by something like 3% unfortunatley you have to have it daily for around six months prior to have any effect. Lots of protein like eggs and chicken will help but don't expect it all to happena few days before. Change your diet now.
Take earplugs in when you do the tests too to aleviate any distractions.
I hope all this helps.
Good luck!