Going winter climbing or mountaineering? Here is a list of things which I take into consideration before any course or personal day out. This is geared towards winter in Scotland or England and Wales.
Planning is a fundamental part in any adventure for it to be a success but especially in winter. Added complications are weather, wind, avalanche risk and snow pack ie conditions. I like to gather as much information as possible before heading out. Here is a list of places I will check multiple times running up until the day.
Weather forecast - Met weather for local updates and mountain peaks
SAIS avalanche forecast for slop aspects and avalanche severity
MWIS for broader weather report
Facebook for pictures of recent conditions- check local climbing and hill walking groups
Having the equipment will make or brake a day out. Sometimes it can also depend on the conditions however here is a list of things I would take that would differ from a summer day in the mountains.
goggles - Use clear tinted or orange tinted so that they work in low light. Often used when spindrift is in the headwind or heavy snow.
Ice axe - Walking axe for mountaineering routes (anything up to grade 1) double axes for anything past grade 2
crampons - Make sure they are compatible with your boots and you have the correct set for the grade of route you plan to do. Just like boots there are different levels of rigidity and robustness.
walking poles - Not essential but really helpful when walking in snow. Usually we are carrying more in winter too so it makes the day easier on your whole body. lightweight ones that aren't screw types as they can freeze and break easily. I go for z poles which fold up nice and small to stow away into a rucksack
insulated washing up gloves - keeping hands dry is really hard during wet days. These can help you keep warm hands and soggy wet gloves. Downside are dexterity and sometimes sweating inside meaning wet hands anyway. Have sure they have a good lining or wear a pair of inner gloves.
Hydration - Instead of using a flask which is too hot to drink and I never have the time to enjoy it on the mountain; I prefer to fill my bottle up with hot water in the morning and use a insulator to keep it a good temperature.
I never carry more than 1ltr as otherwise the weight would get too much; To hydrate I drink as much as possible in the morning and evening before heading out.
lastly there's a saying when trying to manage body temperature during winter - Go Bold and Start Cold - What this means is try not to wear too much at the beginning of a day out. You'll soon begin to sweat which will cause cold higher up and this will also result in you stopping early on to de-layer. Minimising the amount of times you stop during winter is essential to getting back off the mountain in time.
Have fun out there!