My approach is virtually the same as Adams. Like Solo, I typically reserve "wow'ing" or surprising the client with a rendering until it is a $30k+ project.
However, I did render and sign two small $6k projects last week (but the pool contractor that referrred me was happy that he signed both pools). I invested about 2 hours in each rendering, which is a minimal loss of time if they did not buy (but they would not get my 2D or 3D plan if they did not contract).
(Btw, I was quoted in the article - screen name 'Gtrplyr')
Thanks to Adam, who has been a huge help and inspiration, along with all the great contributions here (I am usually a wallflower).
Aaron H