As a realtor, we are a lot of things to a buyer. First and foremost, we are consultant/advisers.
We ask a lot of questions to determine if the buyer is preapproved for a loan, what his long-term and short-term goals are, his requirements and preferences. I think these are critical steps before we even show the first property. I "show" properties by pulling up information online, and together, the buyer and I discuss the pros and cons of each. Doing this, I get a much better sense of what appeals to the buyer and what he can afford; and he, in turn has a better understanding of the market.
And once that need is fulfilled, i.e., the buyer completes the purchase, the relationship continues. As a realtor, I invest in this relationship, I nurture it (by keeping in touch from time to time, answering questions and providing resources as needed). The payoff is in referrals received.
Good service is: service before, during and after the sale.