Document everything you do. Keep a paper log - and I do
mean paper: it can be transcribed to a computer log later (more
billable time!). You can't trust a computer with something
Whistle or hum while you work. I've always liked the Scarecrow's
song from the Wizard of Oz ("If I only had a brain"). Clients have
sometimes asked me to choose something different.
If you are billing by the hour, do not wear a watch.
Programmers should always carry a tool kit. At the minimum,
it should include Philips, flat and Torx screwdrivers, a chip
puller. a soldering iron and a volt meter. These should be brought
to your desk but larger items (like your oscilloscope) may optionally
be left in your vehicle.
Hardware service folk should carry no tools nowadays -
there's nothing repairable in modern computers.
If you are a programmer and are required to provide source code,
deliver it on 5-1/4" disks - or 8" if you can. Bonus points for EBCDIC tape!
For hardware service, always take the machine "back to the shop".
Don't plan on returning it without a court order.
Submit hand written invoices on Post-it Notes TM
. Try to emulate your physician's handwriting and be as vague as possible. Dates of service rendered are optional, but discouraged.
Never submit these until you need money. Think of it as money in the bank (except that it isn't).
Demand payment in cash. Preferably the actual payment should be
made at dusk, in a parking lot or other secluded place. Look
the other way while they tuck the money in your coat pocket. Count
it a week or so later and complain if it is short.
Yes, they do have Remote Desktop, VNC or ssh access. But it's very important for you to be on site because you get mileage and more billable time.
There are other rules you should know, but these are certainly
enough to guarantee your success. Best of luck!