When buying new pieces for your home, especially larger sofas and sectionals, it can be helpful to get a piece of graph paper and draw your room to scale. Then get a second sheet and make scale models of the pieces you want to use in the room. Cut them out and lay them on top of your room drawing. You'll find you can very quickly see how spatial proportion will work, and if anything may be too large or impede a walkway.

Check your egress doors. Some pieces simply will not fit through narrow doorways and the time to determine that is before you order, not when the delivery team arrives. In general, most standard sofas will fit through a 32" wide doorway. More narrow than that and you should discuss with your retailer various options and fitments.