Basically,
- You request flight following (after giving position & intentions, as mentioned, a flight plan helps)
- You are identified and given traffic information
- Once you reach the controller's boundary he/she asks you to contact the next controller e.g. "ABC, contact Centre 123.0"
- You contact the next centre controller "BN Centre, ABC maintaining 6500"
- They will pass on traffic information if there is any, otherwise they may reply with just your callsign.
- You let them know when you are descending or changing to the CTAF.
- Identification services terminated.
Transponder code lasts until your landing (full-stop).
Works very well, although I don't use it often these days. However, I have been significant traffic to another VFR pilot using flight following and traffic information was given which avoided conflict.
Depends on workload - don't be that person asking for it when the controller is working their ass off early morning/late afternoon.