In a list such as a phone book, in a category where I really don't know the firms, I think of several things which narrow the field.

Does the firm have a display ad? I'm more likely to call based on a display ad, because it (maybe) gives me more information than a mere name-address-phone-number ad.

Among firms with display ads, do they give information that tells how long they've been in business? I will often but not always favor an "old established" firm. If I have a special need which not all such firms could satisfy, do they put themselves forward as doing that service? If I'm in a time bind, are they located closer to my house than most of the others? If I have an emergency, do they respond 24 hours a day if I need that? (Note that I know that an emergency after-normal-hours response is going to be expenso plus.) If I'm calling, say for an emergency in the middle of the night and get an answering machine, I'll leave my name and number, but I'll call at least one other, maybe leave name and number, and so on. Whoever returns my call first is likely to get the business in a case like that, in which case I'll call the other firm(s) with whom I left a message and wave them off.

I guess I've gone somewhat beyond your original question here.

Dave Oesterreich