How to stack hotel discounts the right way

Some discounts combine and some cancel each other out. Here's the order that tends to work.

What usually stacks

Member/loyalty rate + a seasonal sale that applies automatically.
A booking discount + a cashback or points portal on top.
Card-linked offers and travel-card credits, which apply after booking.

What usually doesn't

Two typed promo codes — almost always one-per-booking.
A promo code on top of an already non-refundable 'flash' rate.

A simple stacking order

Sign in for the member rate.
Apply one verified promo code if the total drops.
Route the click through a cashback portal where allowed.
Pay with a card that gives travel credits or points.