I believe there is a correlation between the number stamped on the package and which dots.
I picked up one with just the two diagonal dots with 102B3 stamped in it (Target). However like jakesak when I went to another Target the ones with just two dots were clearly clowns (didn't buy any). The paintballers had three dots (see below) and 301B3 stamped on the package. I'm four for four now.
So far it seems to be go through all the minifig packages, locate the ones with the two diagonal dots (ignore the rest for now) and then feel one and match up its dots/stamped number to the rest.