The Walker's Companion: The Ramblers Association

8 Tips For Wild Country Camping (p.85)

• In England and Wales wild camping is not legal without the landowner's permission. In Scotland, follow the code issued by the Mountaineering Council for Scotland.
• Look for a sheltered site, and try to find a flat, stoneless spot.
• Don't camp in a hollow, or too close to a swollen river and make sure you face your tent away from the prevailing wind. 
• Organise the inside of the tent for a quick exit in case of emergencies.
• Don't cook inside the tent.
• Leave wet clothes to dry in the tent porch. 
• Site your 'toilet' at least 100 metres away from water.
• Always leave the campsite as you found it.