There are several ways depending on what you have and how much you want to spend.
1. If you have carpet, you can run the wire under the baseboard around the edge of the walls.
2. If you don' t have carpet you can add some crown moulding to the room and use the open area behind it to hide the wires. Just be sure not to nail into the wire. I'd probably tape the wire down the center of the back before mounting the moulding to the wall so it will all be easier to handle. It won't show once it's up and will keep the wire down the center and out of the way of nails.Crown Moulding example
When placed diagonally in the corner between the ceiling and the wall you have an open area behind.
Corners may be tricky to leave space for the wire to turn 90 deg but you might be able to use these:Inside corner crown block.
If you can run the wire up to the ceiling and then back down to your receiver, etc on an inside wall, it is likely to be non-insulated. This will make it easy to run the wire down the wall to jacks. Where you need the wire to be at the ceiling, drill a hole where the moulding will cover it (worst case you'll have to repair the hole and touch up paint). Then down close to the floor at the same height as your current wall outlets make another hole. Search the net for various ways to fish wire down a wall. The hole close to the floor needs to be large enough for this:Low voltage outlet boxYouTube - How to install Low Voltage Outlet box
Put something like this on each end so you can connect to your speakers on one wall and your receiver, etc on the other.Speaker wall jack
Depending on the size of the crown moulding, you could also run an ethernet cable. Then you would need something like:Wall PlateSpeaker JacksCat6 Ethernet Insert
3. Paintable Raceways for above baseboard
4. Not sure how this looks but there is this option replacing the crown moulding idea above:Paintable Cornerduct