For searching this site, single keywords work well enough - but using single words tends to produce several results that you may not need.
Enclosing two or more words beween inverted commas may produce better returns. For example, "James Francis Smythe" will return the optimum highlight text where those three words are adjacent to each other on a page and written in that exact order. This will save opening up several search results and will direct you to the main page(s) that you may be seeking.
Words searched are NOT case sensitive. "james francis smythe" would produce the same results as above. Dates may also be searched in this way. Example "born in 1920".