What are some of the smart ways of finding related literature online I am in my first year of PhD. I spend a lot of time reading literature related to my broad area of research. I find reading very enjoyable, but finding relevant content online takes up a lot of time. Are there any tricks that people often use to reduce the search time in search engines like "google scholar" (or any other search engines or recommender systems) ?

One thing that I recently learnt was to use the cited by button against each paper in google scholar. I find a relevant paper. Even if it is an old paper, I can find newer works which are based on the original paper and read through them.

Please share some tricks/hacks or tips that help you reduce your time in searching papers online? 

PS - Let me confess that in addition to learning some tricks to increase my productivity, I am also interested to integrate the possible suggestions that I receive here into metrics and integrate them into recommender systems for citation networks, something which I wish to pursue as a hobby project.
I prefer using advanced searches in digital library sites like ACM-DL, IEEE Xplore, and Elsevier ScienceDirect. 

For instance when you search for a particular keyword (e.g., image retrieval) in general search, you would be bombarded with many papers related to the keyword. While most of which is not even directly connected to he matter. In advanced search, you are given the feature to add constraints such as searching for "image retrieval" only within the title. Although this might remove some of the actually related papers, you could be assured that nearly all of the papers resulted from this search is directly connected to your keyword.