a mask will only help minimally bc their main use is for exhaling germs, not inhaling. (why surgeons, meds pro's wear them for surgery) unless you get that other one you were mentioning.
your best bet is handwashing as a few above said. after i touch anything-literally anything i wash or if i can't wash i use an antibac wipe (we still can't bring purell on planes)
don't just think of door handles or others hands here-the knob for the tray table, the knob for the seat back, the knob for the volume on the headphones, the touch screen on the seat in front....my friend is a flight att and she said they never disinfect these things. first thing i do is wipe everything down w antibac wipes.
other thing i do-drink airborne 2x the day before,1x that morning and 1 right before takeoff.
i haven't gotten sick once since is started doing this and i fly about 8x per year. i used to get sick bad every time i flew.