It all starts with dedicated workspace.
Up here in the office, I have two desks. One is for the myriad of Ranch businesses, the other is for my computer consulting business. The wife & dawgs[0] know not to disturb me when I'm at the consulting desk, unless it's an emergency. Compartmentalization is key in any home office.
Household business happens down in the kitchen.
[0] The cats even cooperate, at least for the most part. Go figure.