Before the first meeting, you contact the mentee in a convenient messenger, get acquainted and agree on a call.
At the first meeting, you discuss the goals of the mentee, agree on the schedule of meetings, the place of communication. Write down clear goals for your work, decompose them into weekly goals.
At each subsequent meeting, you discuss the results of the mentee, give feedback, discuss difficulties, set new goals and objectives.
At the final meeting, when the mentee has already achieved its goals, you record its results, discuss its further path, help in drawing up a strategy and say goodbye. Although you can always continue to chat informally in messengers :)