If you're going to do an up-front quote, it's important to have an agreed-upon task list with your client. You don't have to go overboard on it, but if you don'

If you're going to do an up-front quote, it's important to have an agreed-upon task list with your client. You don't have to go overboard on it, but if you don't have anything written down it's too easy for the client to sneak work onto your plate. The case you mentioned where the client nitpicks the design once it's built is pretty common. It's a natural thing to do when there are no constraints on the project. I find it helpful to have an agreed-upon maximum period of time that will be spent on a design review, to be conducted at the end of the project. If the client asks for too many tweaks and you go over that agreed-upon chunk of time, you start billing hourly.