I almost agree!
I like your suggestions for formula's for determining your costs and worth. It's such a simple thing to do, but many individuals don't take the time to do this and seem to just pluck their charges out of nowhere.
I'm not so sure about the fixed-rate billing. We used to just charge for time spent, but are now starting to do fixed price for most decent-sized projects we undertake (these are quoted individually, with contingency built in to cover the risk. I say most projects because we don't do fixed-price for things that are a bit out of the ordinary for our shop). Anyway... and perhaps this is just the way we do things, but I can't imagine fixed-price working for the small 5-60 minute jobs. There's just too much variation in IT. To take your example of "installing SP1 on Joe's PC" - that could cover just clicking Install then leaving it, or it could be you tried installing it, had it fail 15 minutes in, you found the log files and checked the error code, researched it, determined it was probably the anti-virus software getting in the way so you disabled that, but then you found that it was partially installed so gave you a new error... etc etc etc. This sort of thing happens ALL the time for me. I walk in to most jobs expecting it to take 5 minutes, and am often still sitting there an hour later either because of complications like this, or noticing a different error and fixing that at the same time, or being asked to do different work whilst there etc. I understand you can add multiple items to the invoice for each of these, but it starts to get messy. We just fill in a job report and put the time spent. That's what gets charged, and the client can see the work that was done. When there are complications like the imaginary example above we spell them out on the job sheet so the client can see why it took 3 hours to install a service pack.
