An issue I see in many IT parts of an organisation is that niceness trumps honesty most of the time. I entirely support the whole No A*holes Rule, so being nice is a good thing to focus on yet it shouldn’t be at the cost of telling the truth.
Photo from Striatic’s Flickr stream under the Creative Commons Licence
Here’s what to avoid. Do not say yes to requests you know you cannot make. Do not say yes to requests you don’t know if you can or cannot make (qualify it, or suggest an alternative that will allow you to eventually answer yes). Do not say yes to simply what they say – spend some time to find out what they really want.
Telling people truth around what you and cannot deliver is much nicer than simply saying yes because it doesn’t lead to disappointment and it leads to conversations about what you can deliver that works.