To me, there's usually one issue that is more important to me than others. That doesn't mean I am a 1 issue voter guy, though.
However, if I feel that that one issue is so important as to not be ignored, then that's what I go on. Case in point, in the 2006 mod terms, terrorism was my biggest issue and I cast my vote for those would agree with me.
I am not sure if that all makes sense, it's difficult to put into words sometimes.
When Scott began pushing his A rating by the NRA, he got my vote here in Florida. However, I am not single issue voter, I just push some higher to the top with the 2nd being a hot topic for me. Balancing the budget (make that reducing our debt), defense, abortion and dismantling the entitlement programs are first teir issues for me also.