Setting client expectations is really the core of project management. Everything else helps with the first part. - Have a plan and share it, including progress

Setting client expectations is really the core of project management. Everything else helps with the first part. - Have a plan and share it, including progress updates (so they know when to expect things). - Have an agreed statement of work (so they know what to expect). - Think about your risks, write them down and agree them with the customer (so they know in advance that things can go wrong, and can be ready for the consequences). - Bring up issues early, as with all the information above they will be able to make trade offs. They might be more interested in an early build with less functionality, for example. This is just as important on a fixed price contract - although the customer doesn't carry the financial risk, they do carry a reputation risk. Every time you are late without sufficient warning they have to go to their organization/co-workers/clients and suffer the consequences of your delay. That's much easier to do a month in advance than a day in advance of a deadline.