Agree with all of the above statements a thousand percent. If you are really stressing though, I can always suggest reviewing motivational interviewing skills. 1) It's a relatively expedient therapeutic approach to learn and can therefore increase some of your confidence in feeling like you developed a "skill", 2) it has a wide net of utility, 3) you can find handouts with a quick google search and 4) it serves as a great foundational footing for most therapeutic modalities.
This is good advice. One can always default to Socratic questioning or the O.A.R.S. acronym/playbook:
Open-ended questions
Affirmations (where appropriate)
Reflections
Summaries
The most crucial thing, in my opinion, is to be an open, nonjudgmental, accepting fellow entity who is listening very carefully to what is being said and trying to empathize with the person whilst sincerely trying to help but not giving directive advice.
Too much focus on technique (or manuals, or pre-scripted session recipes/agendas) can get in the way of this core process.
Think of a good and effective psychotherapy session as being a fine balance between CHAOS and ORDER rather than simply a process that is supposed to be orderly (by design or checklist) and just play out according to what you, as therapist, would want to happen as some sort of ideal scenario.
The 'CHAOS' comes from the messy, multidimensional, fascinating reality that the client is bringing into the session and this is never going to align perfectly with the 'ORDER' that you think you want to impose by following the manual or some idealized version of how you wanted the session to play out that you imagined prior to the actual session occurring. I think it is important to collaborate with the client in order to keep the session 'on the rails,' so to speak, in terms of implementing evidence-based principles of behavior change (e.g., trying to implement self-monitoring, teaching people to properly identify/label emotions and their physiological, cognitive, motivational, and behavioral correlates, teaching the client to construct and apply his/her own cognitive-behavioral case formulation, behavioral activation, arousal reduction (relaxation), etc.---the list is endless. However if you 'grip the steering wheel too tightly' (to use a car driving metaphor), you're going to spoil the process. Similarly, if you try to exert too much 'control' over exactly how the session goes (without the crucial collaboration aspect with the client), then that's not really going to work out very well (this is where supervision is helpful). If you just 'give up' (take your hands off the steering wheel entirely out of frustration) which is what most VA 'psychotherapists' do if they are not 'implementing a protocol session,' then I'm not sure you could even say that you're 'doing therapy' of any sort. It's a balancing act between structure and flexibility, chaos and order, change vs. acceptance.