After the planning phase, you should have some initial keywords and search terms that fit your topic in mind, and some idea of where to start looking for information. You should pick up good keywords while searching, for example Karelia-Finna can be used here. Find a book in Finna that relates to your topic, open the book details and see what kind of keywords are associated with the book. In many other databases (e.g. Medic, Ebsco databases), the subject headings associated with references are also clearly visible. They are often found under the headings Subjects, Subject Terms, Mesh Terms or Major Subjects.
Databases, websites and other places where you search for information tend to work differently from the point of view of searching. For example, what works in Google may not work in other databases. You may not have an advanced search, or you may not be able to narrow your search in the way you want. Thus it is always worth taking a moment when you go to a new place to see how searches work in that particular database. You should use the database's own instructions for this.
Not only keywords, but also search results are worth saving for future reference. For example, if you have to take a break from searching, it is surprisingly easy to forget the search terms and methods you have used. By writing things down, it is easy to come back to them later. It is a matter of taste whether you prefer the traditional pen and paper or Word and Excel. The most important thing is that you can actually find what you need later on the basis of your own notes.
A search history is available in several databases. The search history also makes it easy to retrace your steps back to your own tracks if you get lost in the link jungle and can not remember where you started. The search history usually records at least the keywords of the searches made, complete search phrases, the number of references and the delimiters used. Some databases allow you to save your search history for later use, but this usually requires (free) registration with the service. The search history can also be manually copied or printed and often the complete search phrases can be used as such in other databases.