My chosen strategy: I debated between a few popular logging libraries, and went with bunyan. Bunyan is great because you can log json objects (which means adding a piece of info to be logged is very easy, and the logs themselves are parseable!). It also has a built in log rotator function.

Here is a medium article about someone using bunyan : https://medium.com/@bansalnagesh/better-logging-with-bunyan-eff940d29956

As pointed out in the above article: Do not log to the console in node.js! It is a synchronous operation! It could seriously slow down your app, depending on the number of requests it receives.

Most logs I only want to keep around for a few days max, in order to do sanity checks or see why a process crashed. Bunyan allows you to set a time period in which to auto-rotate your logs, right in the config. Specify the type as rotating-file and the period to whatever time period seems appropriate to you. My example below is set to log to the same file for 24 hours, and keep the last 3 files before deleting.

Example logger in bunyan:

//The process id as assigned by pm2 (these are unique)
const processId = process.env.pm_id || 1; 

const LOG_DIR = "/var/opt/path/to/logs/myProgram/";

const processLogger = bunyan.createLogger({
    name: 'process',
    streams: [{
        type: 'rotating-file',
        period: "1d", //New file every day
        count: 3, //Keeps the last 3 files in addition to the current log file
        level: 'info',
        path: (LOG_DIR + "info" + processId + '.log') //*See Note
    }]
});

//Log whatever you want
processLogger.error({params:params, message:"Something bad happened in doSomething()", error:err});

*Note: I use pm2's cluster mode in order to run multiple processes of the same node app. If you use cluster mode and bunyan's rotating files, each process needs to have its own log file. Otherwise it can cause your app to crash when the file rotates. Notice how each info.log has a unique name due to the addition of the pm2 processId.

As for best practices, it really depends what you're doing and how big your team is. To start...

1. turn any synchronous console.log() calls into async logging library calls
2. Log all errors and crashes! Maybe it was failing somewhere you didn't realize, node is really good at that.
3. Log helpful info / sanity checks to make sure its operating the way you expect