Advice needed re: a/m enhancements

G'day all

Reading through some of the build logs in the motorsport section here really highlights just how short I am in building my models to a higher standard - despite the time & effort I am spending on careful painting & detailing of what's already in the box.
So...I've decided to change things up & start splashing out on braided hose & A/N fittings, etc to authenticate things a bit more.
As a general rule, what sizes of these sorts of a/m bits do you guys suggest getting a hold of?

Cheers