Single Account.
Documents folder has one named for my Business. Keep all receipts, contacts, phone numbers, ect in there.
Documents folder has one named Source for all code. I store both personal and paid projects in there, each in there own folder, so not to difficult to keep separate.
This allows me to quickly grab content on any of the five macs and five iPads.
I keep all of my personal contacts in my, well contacts. And store notes in two separate folders, one for work and one for personal.
I have several business emails and two personal emails. Easy to stay compartmentalized that way.