Very good to remember:
1) allways write down the frequency given by ATC. If the electrodigits go blank on the main COM, who remember the frequency we were using till then?
2) once received the next frequency, allways verify that the one preselected IS the one received: often happens that it will be changed. Never blindtrust.
3) NEVER preselect the ground frequency during the final approach: it is better to have the APP freq ready during a goaround being busy and under time pressure in flying the plane, changeing configuration, getting out from the landing-taxying-go homing idea had before. On the ground, there is a lot of time to tune the next freq... simple.