Understand the route early
Some homes have an existing chimney that can take a liner. Others need a twin wall system because there is no usable chimney in place.
Once that is clear, it becomes much easier to compare the right products and avoid wasting time on routes the property will not support.
Keep the technical side tied to the room
Most people want to know three things: is the route possible, will it look tidy, and what does it mean for the focal point they actually want.
The route still needs to work properly, but it also needs to feel considered once the room is complete.