Each model of mentoring or coaching will have series of stages which will structure the professional relationship. It is important to find a model that works for you.
An easy basic model covering the stages - preparing - negotiating - enabling - coming to closure - and what they might contain can be found here.
Gerard Egan's model of the Skilled Helper suggests 3 stages of mentoring: Exploration, New Understanding and Action Planning. An explanation of these stages from Keele University can be found here.
A different model, based on Kolb's learning cycle and linked to the stages of mentoring can be found here.
There are many different models and the above are not definitive but rather a few different models to start you thinking about different processes.