Personal Choice is paramount, but I would suggest:
A4 size self sealing bags,
Niceday Grip Seal Plain Bags Clear 224 x 324 mm 1000 Per Pack by Viking
like large sandwich bags. I use them at work so I have loads spare in the office. Sick Sacks are not just for passengers, you would be very pissed off if your first ever, however unexpected, airpuke soiled the aircraft because you had no "Boak Poke" with you.
I wear a lanyard (currently using a Strongbow promotional item) with my Mini Maglite and Digi Camera clipped to it. I know where to find them, I know they can't get dropped and I know they are not going to fall off the seat and foul anything.
I should also mention that when I started out I wore polo shirts, but now I only wear proper shirts, with pockets. This makes the XDA (IPAQ style GPS) and and my iPhone easier to locate in flight.
My kneeboard, which I couldn't do without, has a piece of string tied firmly to it. The other end of the string is wrapped five times around the end of a bic biro which has been coated in super glue. This ensures my pen is not going to fall on the floor and the string is not long enough for the pen to foul the controls.
My spare specs live in the flight bag on the back seat, in a velcro sealed compartment which I can reach when the big bag is restrained by the rear seatbelts.
AP