Let designers pick the themes and plugins

I see a lot of people asking to have web sites built (here, on Craigslist, and in the physical world) who start off by specifying the theme they want used and which plugins they want installed.

This is kind of like going to a car mechanic and telling him to replace a u-joint when what you really want is the car to stop making a clunking sound when you turn left.

If people would phrase their requests in terms of what they want their site to do for them, and possibly how they want it to look, I think they would get better results. A site designer can do a great job if you tell him you want to sell premium widgets to people from a site that you are promoting on Twitter and Facebook. He can do a good job if you also tell him you want a main display section and a single sidebar. Once you start asking him to use the RonaldWeasly3000 theme with a BuddyBar plugin, you are limiting the number of people who will take the job, and the quality of the results you can get.