I have read these same ideas: darkness, safety, herbs/aromas, comfiest, ready nutrition/H2O + a good number of mock eggs to inspire the hormones! Also, keep your "broody nest" near the floor in case she takes to it for safely raising chicks inside of your flock, and so the complications of moving her without breaking her "broody state" could be completely avoided.
Also, a supremely ideal, relatively simple broody nest construction plan available online that allows the lid to be lifted, front access doors, special interior nest lockdown doors and space for the broody and chicks to be highly protected with food & dustbath inside. It is a project I have planned!
But it still depends completely on your specific hen's genetics/upbringing and time of year. I've had all my 3 BROODYSURPRISE! differently bred hybrid Olive Eggers (I thought Olive Eggers less likely to go broody?) and my Buff Minorca step up this year! So you never really know. Also the more expected Buff Chantecler and Light Brahma. I separated clutches to spread some chicks around and give more hens the experience, but except for the team-up I did with 2 of my Olive Eggers on just 3 hatched chicks, multiple broodies raising chicks within a flock can be challenging! Haven't lost a hatched chick yet in my free range situation with a fine young French BCM roo, daddy to all this year's chicks and protecting all! Thanks Nico!