Mentoring is a long term process, so in order to achieve best results, consistency is essential! Keep a schedule, and make sure that meetings occur regularly (once a week is often best). Be sure to communicate when you cannot make a meeting, and remain enthusiastic and professional throughout the mentoring process. Keeping your mentoring consistent will help ensure that you meet your goals, and that your mentoring relationship ends in success.
Mentoring works because of the relationship between mentor and protégé. To develop maintain this relationship, it's important that the pair meet frequently and regularly.