I too use a checklist, it is printed and laminated and sits on the ground in front of me as I prep a jet for flight. I use it every time, start at item 1 and work my way through. Things like fuel valve to closed before fuelling, all aerials in place, batteries load tested, overflow tank attached, fuel filler bung replaced before start up, all air systems pumped up, etc etc. Then I follow the BMFA suggested process for the Tx of SMMART - Switch Tx on, Meter (battery meter ok), Model (correct model memory selected), Aerial (not such an issue now with 2.4Ghz but a check that the LED's on my Weatronic and Multiplex modules are showing correct blink codes), Rates (rates switches etc to correct position) and finally Trims not such an issue now with digi trims but my fav old tx has mechanical trims so it's still valid. Finally to the model I count 4 items - Battery 1 on, battery 2 on, turbine battery connected, manual fuel valve open.
By following the routine of printed lists and memory pnemonics like SMMART I am always confident that everything is ready.