First, take your photograph
I'm assuming you have a digital camera, because the process is much easier if you don't have the delay between taking the photo and seeing whether it worked out, and then having to scan it into digital form. However, you can start with a colour print and scan it into Photoshop if you don't have the opportunity to take a photograph directly.
Any reasonably recent digital camera with some form of telephoto and zoom capability is likely to do a satisfactory job. A file size of 1 meg or more is plenty ('High' or 'Super High' quality).
Tip: Time spent taking the photograph well saves a lot of time later.
So, with camera in hand, we walk outside. Is the Sun shining? Are there any tree shadows falling on the house? If so, go back inside again until it's cloudy but bright. This provides uniform illumination that's essential when trying to change the colour of large areas of the image. This is hard enough, without having to deal with shadows and highlights. Figure 1 shows what not to do.
Figure 1. What not to do
David lives in Canberra, Australia. He trained in Upper Atmospheric Physics, but spent longer than he cares to admit as a Science bureaucrat in the Australian Government. He has been building websites since 1997, professionally since 1999. He is the co-author with Linda Rathgeber of "Playing with Fire", contributed the accessibility chapter to Dreamweaver MX Magic, and other bits and pieces. He has academic publications in areas as diverse as astrophysics and fractal ferns. His interests include photography, restoring golf antiques, collecting old