As Colin says, wear a beanie, and clean socks every night, a few other tips I have are
During the day as Colin says, layer up, and pack an extra layer just in case, try to keep dry, don't just sit in a chair near the fire you'll find you get cold... best to move around, remember a fire warms only one side.
Get a cheap roll mat cut it up so you have a small mat for standing on when your in you pit.. keeps feet warm, and cut it to size to fit your chair... this will make a great difference at night around the fire
Set up tarp so its not in line with the wind, and at night drop the sides down... so to protect you... if you can close one end,
Just before bed eat something warm , I use cous-cous, they are very quick and easy, and gives you something warm... better then a drink less need to pee...
http://www.ainsley-harriott.com/products/ranges/cous-cous
Make a flask of warm drink just before you go to bed wrap it in something to insulate it more, then you will have a warm drink if you wake up cold.. and you don't have to put the kettle on.... if wrapped carefully it will be nice and warm in the morning
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Have a small walk around, before bed get the blood moving this will help warm the sleeping bag.
Last thing at night I take off all clothes as they carry sweat from the day, and any rain you may have had. this is the same reason changing the sock just before jumping into bed, the drier you are the quicker you will warm up, and of course lose heat slower...
If you can air your Sleeping bag during the day... the damp air and sweat will effect the sleeping back performance..
A spare blanket kept near to hand is handy just in case...
A pair of slippers/flip flops... easy to put on if you need to get up in middle of night.. quicker then putting on boots,
Have a pair of gloves near by....
And of course if you are having problems, tell some one.. and let them know, there is no shame in asking for help... ok they may moan when you wake them, but hey better a moan then Hypothermia...
