What's the best overall approach to job-seeking in 2017?

45M, academic science and writing background, with "gappy" work history. Looking for a new chapter, and open to any jobs/careers that pay fairly well (>50k) near Boston. Looking for powerful approaches to getting a new job soon.

Right now, I'm scanning Indeed for appropriate jobs, and sending out (through Indeed) a 1-page resume and 1-page cover letter. This seems like a weak approach. I have no idea if my cover letter and resume is modern and effective, and of course I'm just one among many that apply this way.

Two related questions:

• How can I get basic (free?) insight if my cover letter and resume are well done?
• What other things should I be doing to increase my odds of finding a job? I'm thinking contacting headhunters and seeing if there are some kind of job fairs in the area. Other ideas?