I first wrote this some years ago and it is pretty much irrelevant now so here are the essentials.
You should use a digital SLR and preferably one with a full size chip. You must shoot in the camera’s raw format and transfer the file to your computer at the 16bit pixel depth for processing. Take the time to get the colour and exposure right in Adobe Camera Raw, if you have it, as badly imported files can lose image information that cannot be recovered.
Sharpening. The camera, the camera software and Photoshop can all apply sharpening masks, try and avoid this if at all possible.
Make sure your horizons are straight, try and avoid tilting the camera upwards to avoid converging paralells. and make sure you get the whole subject in the frame. I get too many pictures these days with buildings leaning over and with the tops chopped off. What you see in the viewfinder may not exactly match what ends up on the chip and I also have experience of import software trimming off edges for no good reason. It is better to get a bit further back from your subject, I’m not going to complain if there is a bit more space around the picture if it means it is all there and is straight!
Make sure your equipment is kept clean.
Compacts are pretty good these days. I wouldn’t recommend using them for professional results, but if you have taken pictures on one and think they are of good enough quality then I will look at them. Mobile phone cameras have microscopic chips and dreadful lenses. However big the file the images are no good for routine use.
