Ando
Fantastic advice so far.
The only "technical" tip that I haven't read yet is to save your more "common/likely" flight plans into NAIPS. Speeds up flight planning.
In one of my previous jobs we had our own folders within NAIPS. In them were folders for each of the aircraft that we flew, and within them were the saved routes. All we had to enter were the departure times and SAR times for the VFR plans.
On the non-technical side:
Lifestyle issues, esp. if you're based in a remote area or even a country town. Things like what to bring, mobile phone provider, etc.
You could give advice on CV preparation, how to search for employers, how to apply for jobs, etc.
You may also want to advise them on the pros and cons of AFAP membership.
If it were me, I'd also be advising soon-to-be CPL's that while it's good to have a career plan and to plan milestones; it's also important not to be too "Hungry" or to be in too much of a rush to get that coveted "Airline job" (if that's their ambition). Basically, to enjoy themselves while they are doing it.
DIVOSH!