I'm not entirely sure you can learn SA. My recruiter told me everyone she'd given the tests to either struggled with it or didn't. Her views were echoed by other recruiters I'd talked to. Don't let this discourage you though. Those ARCO books are great, you would do well to get on (I used one too). Also, if you're not terribly familiar with flying, find a flight school in your area and find out how much an intro ride is. Usually you can get an intro ride for $30-60. They don't make any money off it but they hope to hook you. By doing this you can get a feeling for how the view is from the cockpit, far better than a flight sim can provide (the flight sim suggestion is good though).
Please do post your progress on this, i'm very curious to know what works for you and how you improve. Good luck!