Watch a 10 star speedrun: https://www.speedrun.com/sh1/run/y897q0dm

Watch a casual 10 star run on YouTube. My personal favorite is https://youtu.be/XJWoDAgthp8

The only way to pause the in-game timer is to check a save point. Pausing the game, looking at the menu and map doesn't stop the timer. This is good to know as long as you don't accidentally save your game.

If you turn off your flashlight, a close ranged shot will count as a mid ranged shot. This is useful to know for the shooting style requirement, as mid ranged shots are worth more than close ranged shots.

Only use the shotgun during bosses. Using it more often will throw off your shooting style requirement. And don't use the extra weapons. You technically can use them but after a certain amount of usage they will reduce your ranking.

Don't forget to do the Good+ ending and collect the extra items (easier to forget than it seems).

And my best advice is probably, be in the right mindset. It's intimidating and it will probably be a pain, but once you get it you'll think "ah that wasn't so bad."