Many of us have gone through the same getting started struggle you face.  All I can say is “just do it”.  As several others have pointed out, there is no way to know if there will be a better time. 

Paul Merriman, long a leader in passive investing strategy, offers a variety of possible portfolios at http://www.fundadvice.com/portfolio.html#vanguardequity.

Pick one and invest now for all the reasons our friends here have told you.

My personal opinion is to overweight non-US funds compared to Merriman’s suggestions for reasons related to (1) the size of non-US vs. US markets and (2) the strength of the dollar.