A few years ago, Ryan Holiday shared a lesson he learned from Tim Ferriss:

When Tim’s blog was just starting to take off, I emailed him and asked him if he might include a link back to mine. I laid out this clear case as to why — the things I’d done for him in helping launch his book, how many copies it had sold, places I’d secured links for him. He replied really quickly, “Ryan,” he said, “I’ll link to you because you asked — not because of these reasons. In fact, in the future, you’ll have better luck when you ask for things if you don’t try to make it seem like the person owes you. No one likes that.” It was a technique I’ve used many times since. There is an art to asking for and trading favors — the most essential part is the social decorum around obscuring the very thing you are doing.

It’s a lesson that Steve Jobs learned from Andy Grove as well, when Andy sent along one of his employees to learn from Steve, and Steve wanted to charge a fee for the expertise. Andy writes in an email (emphasis added):

You may remember, that from time to time I offered suggestions that pertained to your business. Examples range from porting NextStep to the 486 – – which was in our interest too – – to my presentation to your staff on repositioning NextStep beyond that. I am not suggesting that these are comparable in value to your expertise in graphics, but I gave what I had, put some thought into the problem I saw you were facing – – and it never entered my mind to charge for it. In my view, that’s what friendly companies (and friends) do for each other. In the long run, these things balance out.