I was recently contacted by someone who got a little more than they bargained with when in search of a "spell" they wanted to use with good intention. They met someone in a chat room who professed to be able to help, and it would seem they were covertly 'hypnotised' using NLP techniques. Part of the process involved the person offering to become the person's "master" and teach them what the person desired.
I would suggest caution with anyone, particularly a stranger who offers to be a teacher. In most esoteric circles I have moved it is considered bad form to offer to teach someone, let alone to bed their "master". This is not to be confused with someone who advertises themselves as a teacher, or recruiter for a group. However, those teachers and groups with good boundaries, who are genuinely involved in occult practices tend not to need to recruit through means such as verbal offers of becoming someone's teacher or master.
The issue in the situation I mention has little (I believe) to do with teaching or the occult. It has to do with power and control. It isn't even particularly "magical", although naturally someone using NLP for seduction and control type purposes may well like the illusion that they are a powerful magician capable of controlling someone psychically.
If looking for a teacher, look within first. Use your intuition. Learn from other's (external teachers) as you need to, but carefully maintain your boundaries, and stay conscious and aware of what any "teacher" is requiring from you. Self-responsibility, Self-growth, and Self-reliance are important traits in occult work. While group work and connection with others (the dance of Self with Other) is an important aspect of personal evolution in itself, it is also important to respect your own boundaries, as well as those of others.
While often exploration of the occult is dangerous, it is still worth being as 'safe' as possible, and be weary of the motivations of others towards us. The lure of power-over can be strong, and is often mistaken for being powerful.