I am visible yellow.  Visibility is my main safety concern when riding any cycle on the street, especially at night.  So, I have good lights.  The low height of the tricycle does not seem to prevent drivers from seeing me.  Some wisdom from Dana Lieberman, on the bentrideronline trike forum:  "drivers have a hard time seeing you from the side, not the front and back. Thus, you have to be aware of situations where you become invisible, and ride appropriately".  The only time that I really get concerned about the low profile is when I'm riding through a parking lot, and someone might back up without seeing me.  There is a flag.  I just use the factory flag; I don't feel the need to add any additional flaggage, though I do admire those who fly the laundry proudly.  (Photo from greenman62, on the Trike forum at bentrideronline.)

  My lights are bright.  I actually feel more visible at night than in the day.  I have a NiteRider headlight (32 watts of halogen) and high-intensity LED taillight, which both run off of the water-bottle style battery mounted under the seat.  I originally installed the taillight directly under the top of the back of the rack - but then I realized that the light was not visible from the sides, since it was between the panniers.  The taillight is now installed on the top side of the rack.  (The NiteRider taillight is designed to provide some visibility from the sides.)  For backup, and just extra lighting for high-traffic experiences, I have two Cateye EL-400 LED headlights and a Cateye LED taillight.  I use flashing mode for all of the LED lights (to be seen better).

  I recommend clipless pedals when riding a trike.  Having a foot slip off of the pedal could result in a foot hitting the ground, which could be extremely unpleasant at high speed.  Having a clipless pedal system does not eliminate the possibility of a foot slip, but it reduces it.
  I tried Shimano SPD pedals, but felt like my feet did not have enough freedom of movement, and my knees were at risk.  The Crank Brothers' egg-beater style pedals are much more comfortable.  They seem to allow more 'degrees of freedom'.  The SPD's seemed to rotate ('float') about a single fixed point only, whereas the egg-beaters seem to rotate about any point that I want them to.

  The dual mirrors are helpful.  It is difficult for me to turn my head to see behind me, without accidentally adding some unwanted input to the steering.  I use the miror on the left mostly, but depending on the situation, sometimes I can get a better view out of the right-hand mirror.  And, the dual mirror setup provides a couple of extra hand positions, resting the hand fully or partially on the mirror booms.

  The exercise that I get on the Pocket is highly aerobic.  With the low gear range of the Pocket (thanks to small wheels coupled with standard drivetrain components), I don't need to 'mash' up the big hills, I can 'spin'.