Making the most of one's space can be a challenge.
For us, it was turning a guest room into a home office, but one that could quickly change into a guest room again.
Since I sell books, we decided to do this:
1. Buy a murphy bed or other multifunctional piece of furniture that also turns into a bookcase. Not only will this give you maximum floor space when it is folded up but your guests will have a choice of sitting room or bedroom during the day.
 :  Murphy bed or daybed day bed daybed . I prefer a Murphy bed because it leaves a smaller footprint (takes up less space) when folded up but a day bed can work too.
  For my purposes, the bookcases make sense - and my guests like to have reading material near at hand, too, or a place to keep towels and/or personal items. . If you don't need a lot of office storage, you may opt for one of other variations, including beds that fold up behind shelves, or simply look like a simple chest of drawers when not in use.

2. Make a list of what you absolutely HAVE to have in your office but try to find pieces that will work well for guests too. My desk, for instance,  is small in scale, doubles nicely as a writing desk for guest or a place to sit and read. I also have a comfortable reading chair on one wall, a small chest of drawers, etc. My printer and computer can easily be removed from the room when guests arrive.

3. Try to have a room with at least one closet and shelves and/or hanging bars for clothing. You will, of course, use the closet for Ebaying or office work but your guests will use it for their needs. Closet system s can help a great deal in deciding the best arrangement.

4. Choose a color scheme that is pleasing but not too cold or office-like. Have a picture on the wall that is pleasing for your professional life as well as for the guests. Paintings , print or prints

5. Don't forget to have the "right touches" on hand to do a quick switch transformation. These could include a bedding set , flowers , guest soaps guest soaps , brand new towels (kept on reserve for guests) and perhaps a water glass or bowl of fruit.

6. Try to pick window treatments that aren't too sterile looking. bedroom curtains

7. If you use hardwood floors or other hard surfacing for practicality, consider keeping an area or throw rug on hand to add a touch of coziness for guests. Put it out just before they arrive. area rug or throw rug.

 If all this sounds complicated, I can turn my office to a guest room in 5 minutes flat! PREPARATION IS THE KEY!