Separate electrical circuits for iron vs machines
Work triangles - cutting-sewing-pressing. Don't create a "barrier island" by putting your cutting table in the path from machine to pressing station. Look at traffic patterns.
Agree with getting the lighting designed. We did our own using
Visual-3D and modeled the exact fixtures and bulbs. We used surface-mount LED "wafer" lights so as not to breach the attic insulation value (can lights are awful in that aspect). Get 90+ CRI lighting or colors will look weird (if the bulb doesn't explicitly state 90+ CRI, assume it's 80). Watch out for light placement so it's not behind where you would be at any workstation so you don't cast a shadow on what you're doing.
Don't block HVAC vents or returns
Design storage so you can see items easily but have them protected against dust accumulation.
Consider something like
Home Designer Suite (we used the higher level
Home Designer Pro in laying out our entire home and workshop) to test layouts, cabinet/table sizes, and do virtual 3D walk throughs to make sure the space "feels" good. There are lots of models out there you can download for cabinetry, furniture, even longarms.