If your going via the cabling route then if your running the cables along a roof space/attic, the normal temptation is to run the cable along the floor of the attic, you'll have a lot of mains stuff here so if you can pin the cable higher up. It will means an extra 2-3 m per run, but this will leave you less vernerable to interference (running telephone or data cables for long runs near and parrallel to mains cabling could be a source of future problems).
If you can, think about possibly running the cable into a dedicated network socket
http://www.maplin.co.uk/Search.aspx?criteria=sockets&menu=2&WorldSearch=Y&doy=30m4&C=SO&U=strat15&ShowPics=undefined&MinPrice=0&MaxPrice=9999You don't have to fit the sockets now as if you have flying leads with an ethernet plug at the end to go intoyour pc,you can always fit a socket on the same cable at a later date as persumably there will be enough slack to cut the cable to lenght and still reach th socket, it's easly done, same as fitting an extention socket for your telephones.
The advantage being it's tidyer, a flying lead is venerable to being damaged by passing traffic, furniture, vacum cleaners, etc. that way you only have a lead from the socket to pc which could be unplugged and if need be; replaced.
Also (I've never done it myself) I've heard fitting the plugs on the end of the cable isn't the easyest thing in the world to provide a reliable connection long term. (This is just hear-say I've picked up so I could be wrong on this point).
Pin the cable to the top of skirting boards (or if they have a moulded profile cables in part disapear within a scroll of a shaped skirting board. And go around door frames. if you need to go along the wall through the ceiling then if you can try to do this above a door frame so as little cable is visible along the wall.
Pre plan your route before running a cable, looking out for pipes cables,heaters, furniture to go behind.
Definately avoid running the cable along the floor and certainly dont go along the floor part of a doorway, this is a guaranteed fault in the future as foot traffic WILL ware the cable out in time, even under carpet tucked behind the carpet gripper which is a common cause of faults in it self, you'll be suppised how much carpets move, and this will eventualy pick the cable up and pull some of it on the tacks of the carpet gripper.
If going through cavity walls or through ceilings into a void above a short lenght of the springy net curtain support is a handy way of getting something through if the cable is reluctant to get through.
If you have an avalable route for the cable but it's tight or impossible to get in the gap see if a say electrician friend has a "Mouse" or other wise known as a "Foil mouse". Its a real of spring steel about 8mm wide which is stiff enough to push from one end to feed the other though a long run. Flipping the end causing a wave to travel along the foil will get the far end to go over a joist in the way even from 50m away. It's a great tool, I used mine the other day to reach 40m across a large room in the cable space in the ceiling, going over cables and around dips and all from one end so I only had to climb a ladder twice instead of doing this every 2-3 m.
