I noticed that if one wants to get into a new branch of mathematics it is really hard to find good literature to start with. Of course, if one googles the name of the subject one will find a 1000 pages book that contains all the established theorems and proofs. But as a start, an informal survey article is probably more helpful. How do I find such articles? Should everyone in each specific case go to their professor or is there a uniform place where one can look for such literature?
I also noticed that one of the main problems one has if one wants to start doing research is that it seems all people involved in the current literature (who write all the new research papers) know all the usual tools that are used to solve problems of a specific kind, and if one wants to start participating there is the feeling that the preknowledge is missing. But this knowledge is maybe only communicated orally from professor to their PhD students, and as an outsider it's hard to find appropriate literature. But if there is, where can I look for it?