You can also do an advanced search, which helps a little bit. Check it out because it allows you to refine your search. And I guess you know by now, that putting things in quotes, limits your results to items that have the same word string.
It would be helpful to know what types of searches you are doing that aren't giving you the results you want. For me the biggest problem I have is when I am searching for news, I want the most recent ones on top, but that is where the advanced search helps.
You should also note that a few of the first results are sponsored links - they pay to be at the top of the list.
There is also an option to block results from certain sites, which also helps narrow it down. So if you notice that a lot of the useless sites are coming up, click on block these sites, but it only shows up sometimes.
There is a red marker on the left side of the page called search tools, that helps you narrow it down.