What I usually do is:
1) Start dash dribble (R1) in the centre circle just inside your own half.
2) After about 2 dashes, the ball should be just about the right distance away from your player. NOTE: It will be good to also change direction if you can between the dribbles.
3) During the "lag" time between pushing the ball out after the 2nd dash dribble to just before your player reclaims the ball, hit the shoot button.
4) Depending on your players' stats, you have to vary the power of your shot. Generally speaking, the longer the "lag" between the dribble and shot (or the longer the amount of time your power bar appears before your player hits the shot) the harder and truer the shot will be.
5) And as mentioned, remember to control direction of the shot.
Totti is a very good player to attempt this because his stats are perfect: Dribbling accuracy, shot accuracy, shot power, shot technique, technique. Of course, you can go all boring and attempt this with a certain Portugese superstar at Real Madrid but where's the fun in that eh? =P
Happy hunting!