As blogged on Gainmode.org, improper wiring in a house raises the risk of fire and electrocution. However, with a little planning, the risks can be successfully avoided. Also, placing the switches and sockets at the correct height means that you will not have to bend or jump to use them. And admit it, dangling wires are a nasty sight too.
Although electrical wiring should preferably be done by certified experts, in case you want to go the DIY way use this guide that we created keeping convenience and safety requirements in mind. Also, do not forget to have it inspected and approved by a local building inspector.