How do I orient myself to the literature concerning a research topic and not be overwhelmed? I'm in my first semester at a Master's level program in mental health counseling, and I have aspirations of perhaps eventually getting my PhD. I'm presently working on a project for a class about PTSD and after about a day of digging, I found a plethora of theoretical models; some of which are older, some of which are newer and have been built off of previous ones. Traumatology is a much larger and more developed field than I had initially thought, and there are numerous complicating issues, one example being the interaction and overlap with dissociative features/disorders and developmental pathways and models.
I'm starting to get overwhelmed by all the connections I'm seeing and all the articles and books I want/have to read in order to do a half way decent job, and it doesn't help that I'm on a time crunch.
I have had this experience in my undergrad a bit, but managed to scrape by with a research paper that didn't end up amounting to much. I was not satisfied with that outcome, and don't want to repeat that in any of my Master's level courses, but I find myself uncertain of what effective research even looks like or what to expect from myself.
I have 3 questions, the first two are iterations of the same question.

How could I orient myself in the literature of any given field without &quot;getting lost&quot; when pursuing a research project, an overview, or even just a rudimentary understanding as the basis for a question in a different field that has some interactions or influences with the one I am investigating?

For instance, perhaps I decide in my PhD to develop a project on topic x and want to include perspectives from fields y and z, which I have a good foundation for but am not intimately familiar with the literature or theoretical models of the fields themselves.

How do I know when I'm trying too hard to understand/give an account for a phenomenon that is not immediately and directly relevant to the topic of my paper?

For instance, if I'm really interested in doing a paper about the relationship between some particular feature of the interactions between pathology A and B,  but I get caught in the weeds in trying to understand/explain to the reader competing behavioral models for understanding A and contrasting the cognitive and behavioral models for B.

How do you deal with feeling overwhelmed when doing research?
Start with well-written review papers. These are designed to do exactly what you ask: to orient a reader to the state of knowledge in some field. If you are working on something multidisciplinary you may need a separate orientation for each discipline if there isn't a good review that already makes the connection for you.
Then, once you are oriented, you can start to dig. Try to discipline yourself towards pursuing a specific goal in your literature search. When you find offshoots, label them as future places to dig but don't start excavating them quite yet.
Other than that, try to stay organized. Organize your thoughts by writing down what you are learning, make concept maps if they help you, or start organizing references into nested bulleted lists. Be open to reorganizing as things develop.

I want to add an addendum concerning your specific field of research. Published science in biology and medicine, and even more so in areas related to mental health/psychiatry/counseling, may contain a lot of conflicting information. These fields deal with some of the most complex systems humans know of, and our core knowledgebase is extremely lacking. If you're used to reading textbook descriptions of &quot;how things are&quot;, the actual academic literature is by comparison extraordinarily muddy (this is true of all fields, no doubt, but I think especially the ones I've mentioned). It may help to know to accept this, and to not treat any one paper as Truth. There are competing models and competing hypotheses and competing approaches to treatment because none have yet &quot;won&quot;.
Adding  from a comment: if you are wondering how to find review papers...
There are some journals that only contain reviews. Some of these are good journals (and since reviews tend to get cited a lot, you can often discover them by their very high impact factors), some are not (these will tend not to be cited much). Some indexes, like PubMed, allow you to filter for only reviews (I don't know how accurate these filters are). Otherwise, adding &quot;review&quot; to a search string will help. You won't get all reviews, but many of the top results will be.