I had not much opportunity to work on it until now, but in categorizing the principles at work in successful psychological interventions I'm following the identifications of psychotherapy researcher Prof. Klaus Grawe.
Area I: Analysis
(1) Problem Actuation & (2) Motivational Clarification
The following schools are providing intellectual resources to be integrated in this area: Psychoanalysis, Gestalt Therapy, Psychodrama and Family Therapy. Alas, besides Gestalt Therapy, they are all apolitical and must therefore be reintegrated with socio-political class analysis. It is false to exclusively focus on the internally caused origins of the diminished life contentment of the client. It's origins are oftentimes, if not almost always, to be found in the anti-capitalistic policies and the strategemic communication of certain classes. To be able to spot all sources of irrationality, the principles of critical thinking (and especially the systematic search for informal fallacies) must be applied here. Logic and contextual thinking is the key to mental health.
Area II: Solutions
(3) Resource Activation & (4) Competence Mastery
Besides Cognitive Therapy (i.e. logically consistent thinking), the most important school to be consulted here is Behavioral Therapy in all its forms. I'm especially thinking of Self-Assertiveness Training to fully release the client's socio-communicative resources. I also consider professional speaker training (as practiced for example by Toastmasters) as an important part of self-development. If you can't communicate powerfully your values, absolutely nothing will change in society and your personal life.
Psycho-pharmaceutical medication and Behavioral Therapy (or in our context: Behavioral Training) are empirically proven to be the best behavior modification techniques. The problem that comes with powerful solutions is that they also can cause harm, when they are resting on wrong philosophical views and/or wrong political analysis.
The ~values~ that are to be achieved by behavior modification techniques are to be defined by an objective science of ethics, and not by a politically correct therapist who votes for a semi-socialist party, flirts with eastern "philosophy" or naturopathic treatments, and which biggest problem in life is how to save the whales. Alas, this description fits to most contemporary "therapists" in Germany. You can easily spot them by their view that wearing a tie or neat shoes would turn them into the equivalent of a "fascist"...
For me skills in critical thinking are of highest importance. I'd very much like to offer courses about it embedded into an Objectivist framework. Interestingly, in Germany no such courses seem to exist, and the state-owned schools are not offering them either. Perhaps I can close this gap somehow. If I remember well, Cognitive Therapy has identified frequently occurring logical fallacies in irrational thinking. I imagine offering checklists based on these findings for all life events that one can imagine.