Okie lah... if everyone is using long lens, then have chance. Below is the shot at 200mm F2.8 on a crop:
There are 2 paths to bokeh that is good and "gao" (as in kopi-o peng gao siew tai etc., for "thick").
First, use a long focal length (perhaps at least 200 mm) and as big as you can afford aperture (at least f5.6).
The good point is that bokeh quality is generally smooth at long focal lengths (diffused) and alot of lens are cheap and good through this technique. eg. 70-200 f4, 70-300...
The negative is that it can be at times painful to stand far, especially painful if you are on crop factor... you will be subject to the mercy of other photographers infront of you. Nor will people buy you liang teh if you get a sore throat shouting at models from afar aft 2 hours. :bsmilie:
Second, use a prime lens with a moderate focal length (50, 85, 135) boasting big apertures (at least f2).
The best part of this is that you get alot of isolation even at these perspectives...
Sadly, most cheap primes in this region feature awful bokeh quality which may be disastrous for portraiture (many 50 mm lenses are this case) You could pay thousands (eg. 85L, 50L) just for "nicer" bokeh... but bokeh will still be slightly inferior when on crop factor.
What's more, focusing at f1.8-1.2 can be a pain to get used to. And getting used to focusing is just the start of the ball game when you realize that the Kelvin (chief calibration staff) at canon service centre just became your best friend.
Which path is the best? It's up to you? I've chose the later.