There’s a good article in Sky & Telescope on comets 252P/LINEAR and the smaller fragment P/2016 BA14, explaining observation opportunities. A comet hasn’t passed this close to Earth in 246 years. And as it does the wonderful green halo around 252P/LINEAR is sure to grow but will probably remain around magnitude 6.
As the comet flies by Earth it will sweep through the constellations quickly and then fade back to below magnitude 12 in short order. Therefore try not to miss it.