Confession: I often start a research quest with a simple Google search. Keeping in mind that not all the information I find on the web is going to be reliable, Google is still a good way to get my feet wet with a topic and gather the relevant vocabulary I need. Then I can move on to a more targeted database search.
What is the relationship between vacuum energy and dark energy?
Step 1: Break up this research question into two or three main concepts. Ignore extraneous words.
Step 2: Conduct an initial search with these words, and quickly scan the results.
Step 3: Using information from your initial search, add synonyms, acronyms, and variant spellings.
Step 4: Conduct a more targeted web or database search.
Repeat steps as necessary!
(vacuum energy OR zero-point energy) AND dark energy