Qube & Banshee - How do you go about clients who try to swindle you with regards to sneakly adding extras to a project if you charge on a fixed price?
Experience, cross referencing body language and conversation directions for one, and understanding the task sufficiently to ask all the necessary questions. In terms of software, get the design complete and on paper or alternatively as concise as possible. Such as recently I had a full project spec which read, "Grant "read&write" access to "everyone" on all files uploaded onto the server regardless of OS permission settings.", thus PermissionsFixer was born, the single most ugliest software ever developed for any Unix derivative ever, in the history of software. But it works.
I dont do twiddly features when it comes to software, too often business customers say "we like it, but we want that button blue and we want the search results to return this item first..." - if I think i'm going to get any of that and the 6 months tinkering and backwards and forwards time dealing with ammendments makes, then I let some other mug get the job.
If i'm not totally confident i'm going to come out the far end smelling of roses then I dont bother with it, but i'm lucky enough to be able to pick and choose my work. So no, i'm not doing that blasted Karaoke system I keep getting asked for.