What is the best financial tool, or approach, to retirement for
someone starting at age 49?

49 is an unfortunately late start for retirement planning, but late is
far better than never.  You'll likely have to work beyond the normal
years of retirement if you want to maintain a decent standard of
living, so do keep that in mind when making your plans.

Vanguard is the best company by far that I've found for retirement
investing.  They have tools to help you know how much and where to
invest your money and they offer much good advice on avoiding taxes
(legally of course).

Here is Vanguards personal retirement page:
http://flagship5.vanguard.com/VGApp/hnw/content/PlanEdu/Retirement/PEdRetInvHwToInvForRetContent.jsp

Read up and walk though their steps.  It'll be a big help.  Then get
started with investing ASAP.  They can do automatic monthly
withdrawals from your checking account so you don't have to worry
about ever sending them a check.

Best of luck in your retirement planning adventures!