Most of its been said here already, but my thoughts and what works for me is
I use the right sleeping bag for the season
I don't wear socks, but love a hot water bottle, either an empty coke bottle (1 or 2 litre) or a 1 litre fuel / drink aluminium bottle (wrap in spare clothes or in the case of he 1 litre fuel bottle I put it in two socks). The water is still around body temp in the morning and boils that much quicker
Eat something an hour or so before bed time, this gives time for the digestive system to kick in and release some fuel into the body while you sleep
Stop drinking about 30 minutes before hitting the sack especially at my age, my son hates it when I try and use the pee bottle, miss, and hit his bag (your aim goes bad along with your bladder and eyesight as you get older)
If the weather is warm you can drink right to the end as you don't mind getting up for a waz on a nice night
Get in you bag before you are really cold, remember, you are heating a lot of cold air when you first get in. A small gas lantern or even a candle lantern in our Hex 3 throws out some welcome BTU's, but watch the ventilation and DO NOT leave on all night
Keep something to eat and drink close to hand for mid night nibbles, maybe a bit of cake, chocolate, digestive biscuits etc, give you a mid sleep cycle energy boost, it you wake up cold and hungry you need to eat something.
Make a Thermos of tea/coffee/hot chocolate, if you don't drink it in the night, its very welcome first thing in the morning
With enough food, drink and insulation and pre supposing your bladder does not wake you up, you should sleep fine
Just my pennies worth