Just because you got many results doesn't mean you did a good search. The important thing is whether or not the results are about your subject of interest. A good result list contains:
The number of publications that you will get not only depends on how well you have designed your search query, but also on how much research has been done within the subject.
For a course project or a student thesis you will need to define your question so that it is neither too broad nor too narrow. When doing a search in a bibliographic database, ideally you would like to get a number of results where you can at least browse through all titles. What this number is depends on the size of your project (and your ambition) but in general it could be something between 20 and 200. NB! These are general guidelines and not absolute numbers!
When using Google for everyday queries we are used to getting thousand of hits and will generally only look at the first few pages until we either tire or feel that we have found what we were looking for. However, doing a search for scientific literature is different from asking "when does the supermarket close?" or "what is the boiling point of gold?".
There is seldom one single answer to scientific questions and therefore it is important that you find and look through most relevant publications within your subject, covering all (or most) aspects.
You're not meant to read all publications from your result list. First, you read all the titles and select those that appear most interesting. Next step is to read the abstracts of the selected publications. After that you make another selection to choose which ones you will read in full.
Don't wait too long to start reading. If you find an article that looks very promising - read it! If you find a new good search term in the text, there is nothing that is stopping you from taking a step back and re-doing the search to see if you find something more interesting.