It's that time of the year where I go through a box of tissues a week due to a runny nose.
How can I optimally use a tissue so as not to waste that much while at the same time not getting any on my fingers?
Don't crumple; Fold.
...And fold carefully. Fold over or in half the soiled part once or twice and then re-use the dry area. Do that as many times as you might need. Maybe 2-4 times per tissue.
You can tear each tissue in half before you use it, thereby getting two uses out of each tissue. Make sure to tear along the grain of the tissue paper, which is (in my experience) along the main crease in the tissue. You can stuff the unused half back into the box for later.
I used to have the same problem. I would go through a whole huge box of tissues with every cold. And... now I don't. It is very rare that I need very many any more. I don't know why this changed... but it changed at the same time I stopped eating anything with pesticide, perservatives, artificial color/flavor, etc. and eat more saturated fat (especially butter and full fat milk), and avoid anything processed. (which was about 10 years ago).
Also anything you can get with lots of proper vitamin D3 (possibly not synthetic added stuff like in pasteurized milk) should help, but you have to take it earlier ... maybe before the symptoms. Organic butter made from milk in the spring (which looks more yellow but does not list color in ingredients) is one good food source. Another food source is liver. A good natural suppliment source is cod liver oil. And the best source is sunlight... which is not in good supply during the winter, which is most likely why colds are more common in the winter. The idea of temperature having anything to do with it is not supported in any scientific way.
Also I find that drinking less water, or drinking less at once, spread out over more time helps... but can't say if that's healthy or not.