What this usually brings is more flexibility and a low budget - at least at the beginning.
Classical style of IT then:
- Internet ADSL connection to home office
- E-Mail (along with spam filtering) hosted at the Internet provider
- Single notebook or desktop PC with some backup strategy or a dedicated server + desktop pc + laptop (something like this). Newer Internet provider modems are even shipped with an option to plugin an external harddrive that is directly offered as a network storage service for connected (W)LAN-devices.
- All-in-one printer-scanner-fax devices for doing those most important office operations dealing with paper where still necessary. Usually small and compact devices do not occupy too much space and can handle the small amount of paper in a modern office.
- Contacts are saved in the address books of the used email-client, in some cases additional simple local XLS files or Access databases are used or also free online services (but only surprisingly seldom - I guess people do consider their business contacts as a company secret and do have privace concerns).
- Office application package is intensively used for writing letters (where still needed), contracts, agreements, invoices and the like.
- PDFs are created from the office documents written or scanned documents are saved in PDF format for (long-term).
- Sector or branch specific software applications (e.g. banking or insurance agency tools) move more and more in the direction of being online services (web applications) rather than applications that need a local installation.
- With a smartphone they can answer emails also while on the road which is crucial for a one- or two-man/women show.
- Appointments are managed in the smartphone with the smart phone's own application, Google Calendar or in a classical pen & paper style (what is actually used is mostly depending on people in the company and branch).
Related posts: Why Linux?, Going Linux, Why I switched to Ubuntu, The small software vendors.