Tracking aircraft movements

[camerashy]

Sorry if this is a basic question but stiil learning the Uniden 3500 and frequencies.
My local airport is Manchester so I have a number of frequencies set into my System eg: Director; Approach; ATIS; Ground; Runway No; STAFA ( which I think is aircraft coming in from Derby area) and Kelsall ( aircraft from the north)
At the moment I'm picking them up on any Manchester airport frequency and through their callsign then locating them on Flightradar24.com then tracking them as best as possible.
If for example, they are coming into Manchester should I move to the new frequency they are given by ATC (which sometimes is difficult to pick up) or should I move to the Approach/Ground/Director frequency etc and wait for them to establish contact.
Or am I doing it completely wrong
Thanks
Dave
PS posted elsewhere as I think this may be the wrong section