In a previous article called Into the mind of a climber I said "In the mountains I found I made bigger advances in my progress when I changed my approach rather than any physical training." This article details some of those changes that I made that allowed me to push my winter climbing. This is was written with Scottish winter climbing in mind, but could be translated to most forms of climbing in the mountains.
I will rack my gear according to what I think I'll need on the pitch. This is commonly done on rock, but took me a while to start doing it in winter as well. I will continue to do this as I climb the pitch. Planning ahead and moving the gear that I think I might need to the front of my harness and even putting a certain quickdraw on a bit of gear preemptively. This can be done when at a good rest and saves crucial time and "pump" when on the crux. On a steep route with a ticking time bomb before your arms uncurl and you fall off, it is crucial to be quick with your decisions and placing gear, hanging around will get you pumped. Again for this reason I will often save cams and quick placing gear for the crux. Just be weary that cams can be hit and miss in winter if the cracks are icy.
I also plan ahead in this manner with axe and crampon placements and try to work out a sequence similar to what one might do on rock. I might go up and down from a good rest on several occasions to assess which placements are best and brush snow off small footholds to make sure I don't miss anything. Once I have a sequence in my head and have ideally placed some overhead protection I can then blast through a tricky section with confidence.
Full nights sleep
I used to sleep at home in Glasgow before winter climbing then drive up early in the morning. This would sometimes mean a 3am wake up. I noticed I would regularly be falling asleep on the belays. Instead now I always drive up the night before and get a full nights sleep just a short drive from where we are meeting. This means you are function a lot better and can think clearly.
Between breakfast and dinner, which on a winter climbing day could be 16hrs apart, I used to just eat a Soreen loaf or a few mars bars. I even had a friend who used to eat a few celery sticks. As you can imagine this is not going to fuel your body and will lead to poor decisions being made and a lack of energy. Constantly eating chocolate also isn't great if your out often. I now make 6 tuna mayo sandwiches and eat them at 2hr intervals throughout the day. I also switched from water to flasks of tea. This A) doesn't freeze and B) is far more appealing to drink than freezing water when you are cold meaning you are better hydrated.
I have also made changes to clothing. Climping in thin gloves allows for a much better feel of the axe. There is nothing worse than baggy gloves when you're pumped, you will fight twice as hard to prevent your hands uncurling off the axe. I will wear a single skin of fabric on my pams for the hardest pitches, not dissimilar to a golf glove. This only works when you are pumped and have a lot of blood flowing to your hands to keep them warm. Make sure to carry a big range of gloves for different pitches and situations. I will tend to carry a hard leading glove, a seconding and mid grade leading glove, which I will do the bulk of the days climbing in, and a big emergency/belay glove on a given winter day. A lobster mitt (mitt with one finger free) is an extremely good option to carry as it almost gives the warmth of a mitt, but the added dexterity allows you to continue placing gear and can be used for leading relatively tricky pitches.
I also tend to wear much less on a hard pitch ( just 2 layers). Again this only works when you're working really hard and warm enough. This means I'm not restricted in my motion by many layers and don't overheat. I carry a huge belay jacket which I can then put on as soon as I reach the belay. For a long time I didn't have one which is fine on easier ice routes where each pitch doesn't take too long and you are constantly on the move. However once I started trying harder routes where you could be on the belay for a matter of hours I found I was starting climbing each pitch freezing cold, this does not produce good results. A big belay jacket like the Mountain Equipments Citadel is a great piece of kit. It is also a great safety backup for if something goes wrong.
The other clothing adjustment that I made was switching to soft-shell if I ever plan to try a hard route. These allow you to move so much more easily and are able to keep a dusting of snow off. However make sure to check the forecast and if it looks warm and wet go with waterproofs. The bottom line is clothing is a very important factor when in the mountains and needs to be constantly dynamic to suite your needs.
With that said weather and conditions play a big role. Check the forecast and know that weather and conditions will make the greatest difference to the difficulty of your day and be aware that a given route will feel much harder when conditions aren't favourable. Maximise good days and expect to struggle more on bad days. Take time to learn what type of routes will be easier and harder in certain conditions and don't set your heart on a certain route no matter what. Be patient and search out the good days for your big goals.
Fully functioning kit
Making sure crampon and axe points are sharp also make a huge difference. A good climber should use their feet well and having razor sharp crampons allows you to put your feet on mm size edges. This drastically opens up the number of foot holds available to you. I sharpen my axes and front points every night before getting out and expect to replace picks and front points altogether once a season if getting out regularly.
Climbing in a 3 is usually a hinderance, however if trying a hard winter route I would always opt for a 3 where possible. This has many advantages; splitting the gear up on the walk in, someone else to break trail, a buddy to chat to on the long belays, breaking up the hard climbing with an extra fresh pair of arms. A bonus is that should someone become injured for whatever reason there are then 2 people to help them instead of one.
Taylor it to your needs
The list doesn't stop there. You should keep critically assessing what is making your day harder and how to improve. I know many friends who have made modifications to their kit for this reason. Such as velcro on top of Helmut and inside of hood to stop it coming off when it's windy or when you twist our head. Attaching a plastic buckle to crampon straps to make it easier to put them on with gloves. Chopping off and adding on parts to a rucksack. Even inventing new bits of kit that don't yet exist such as a big hanging bag that ca be filled with snow to bivi on on a Himalayan peak. The list goes on.