Yes would definitely second Casey's Law's link there to the beginner section!
Speaking personally I had an extensive look through the miniatures gallery for each faction, then watched the faction videos, and went with the ones which models/style appealed to me the most.
As a general rule Infinity is a little more tactical than many other wargames - there are still strategic (list building, choosing units etc.) that are important, but you can buy something because 'it looks cool' and still find out that you can use it in your army without any nasty surprises and finding out that it's crap - unless you go mental and buy 3 TAGs (the big robots) directly or something
Please fire away though if you have any questions!