In Steve Friedl’s insightful screed “So you want to be a consultant…?,” we find the following advice:

A final note on time management: with ongoing customers, there will often be low-priority background projects that can be handled more or less at your convenience – e.g., “anytime in the next few months” – and these are great to have in your back pocket during a slack time.

But many of these long-term customers have a kind of unspoken limit on how much you can bill them in any given month, so there is only so much of that back pocket time you can expend all at once. Of course, if there is a disaster and you have to dive in, it takes what it takes, but most customers will call a time out when the invoice level reaches a certain amount.

You’re likely to run into a circumstance where you have things you could do for this customer, have nothing on your plate for anybody else, but have already reached that unspoken limit: if you go over, you’ll probably get paid, but it means you’re not going to be trusted to keep it reasonable in the future and will be subject to heightened scrutiny.

At the end of the same section, Steve offers the consulting maxim: “You must know how to read your customer.”

I recalled Steve’s writings as I was preparing my monthly invoices. I had performed a lot more work than usual for one of my clients. At the end of the third week, the client OK’d extra hours to finish up an important release; but even so, the final numbers came out larger than I expected. I had a gut feeling that, although the client probably wouldn’t object to paying the amount, it might raise some eyebrows because I just barely crossed over that magic line (in this case, the one where you add a digit). I had to decide whether to stand on principle and bill what I had rightly earned or give an hour and a half towards keeping my client contented. Naturally, I chose the latter.

I wondered if I should tell the client about my free hour and a half of service. On the one hand, giving the client an explicit credit should contribute to their good feelings. However, my decision also raises some bothersome questions: Why do I feel compelled to do it? Do I feel guilty about the number of hours the job has taken? Will I be giving them credits like this in the future whenever I exceed a certain threshold?

In the end, I decided not to tell the client. It’s only an hour and a half, after all. If it were significantly more, you bet I’d make the most of it. And if the client had been riding me with a whip, I would have billed every penny — magic line or not. Instead, the client was grateful for my extra time, while letting me set the limit. So I’m investing that hour and a half in good karma.

Consulting is more about dealing with people than it is about anything else. So as Steve says, you must know how to read your customer. Every situation is unique — with other clients I might have handled the same hours quite differently.

This principle applies to a lot more than how much you can bill. For instance, each client has their own tolerance for how frequently you update status — some of them want a daily update, while others don’t want to hear from you until you’re done or a decision requires their attention. How much authority you’re granted to make those decisions on your own is something else you have to be able to read, because the client is often unaware of their own comfort level in this area.

How long it “should” take to get a job done is often another unwritten limit — but it usually doesn’t even need to become an issue. Deliver incremental updates frequently, and the point becomes moot. On the other hand, if each update triggers a “so what?” response, it may start to look like you’re staging a productivity theater. Make each update count for something.

Reading your client isn’t all about eliminating the negative — you can also use it to accentuate the positive. Once you learn what makes your client tick, you’ll be able to find those things that really make their day without costing you a ton of effort. What’s important to them? Making them look like heroes to their customers usually ranks right up there in my experience. What could they not care less about? The font in your status report comes to mind. Unless you use Comic Sans.

It’s good to take as much of the guesswork out of the client relationship as you can, and the best way to do that is to talk to your client. Ask the client about their expectations; they may not always be honest with you (or they may not even know the real answer), but the more you can establish the rules of engagement, the less you’ll have to make them out on your own. Thus, I offer an additional consulting maxim: “When you can’t read your client, request a larger font.”

Get weekly consulting tips in your inbox
TechRepublic’s IT Consultant newsletter, delivered each Monday, offers tips on how to attract customers, build your business, and increase your technical skills in order to get the job done. Automatically sign up today!