The words/terms you choose are very important! Start with exploring freely, use for example Google Scholar to find a few papers that appears to be of interest and collect keywords from these. Try to think of as many different words as possible to describe the subject you are interested in.
If you are searching for scientific literature you should use English words as most scientific literature is written in English. If you are searching for species, add their latin name.
However, just because something is the correct English translation of a concept, it is not necessarily the word that the researchers in this discipline are using! You need to figure out what words the researchers within your subject use to describe the phenomenon you are interested in. Sometimes there is one particular expression that is most common, other times there are many synonyms and alternative expressions that are being more or less equally used and then you need to include them all in your search.
Here follows a few examples of synonyms, alternative expressions and alternative spellings. In other words, if you are interested in one, you are likely interested in the others and should therefore include them in your search: