Truth is, at least speaking for myself, I use a combination of my font management programs (with preview), a collection of font catalogs I have built over the years, sometimes font foundry web sites and catalogs and 35+ years of working with type styles or fonts as they have come to be called. My experience began with "Hot lead", "Photo-type", "Press type", hand layout of letter styles for hand lettering and finally to the good ol' computer. It also helps to own a "massive" library of fonts.
may i ask how u guys/gals figure out these fonts... do u have a font preview program? Or just experience... Because i just cant figure them all out... just thought i'd ask.