There's forgotten dimension being a good consultant and that's to only make sales when you have the opportunity and ability to remain independent and be able to provide recommendations that your clients might not want to hear, but need to hear. Too often, consulting firms incentives are aligned to making the sale and getting the next cheque that they'll be willing to compromise on their recommendations and solutions in order to please a manager within their clients - often whom have a specific thing they want to achieve which might be unaligned to the overall client's best interests.

Because of this, consulting exists somewhat differently to startups as well. In the startup world, your aim is to delight the customer. If you apply that same principle, you'll be tempted to say things that make people happy. I'd argue proper consultant or advisor in any field (whether IT consulting or management consulting) must be able to make a judgement concerning their expertise or their analysis regardless of what 'wants' to be heard by their prospective client (in lieu of how much they might be paying them).