you can clean/ them with 1:10 ratio bleach:water, to kill any bacteria/mold, dry them being careful not to break the skin, you can then store them in a dry dark area for a few months.

so...i'm frustrated woman! i just tried and still am so perturbed i am incompetent to post pictures here..hehehhee...i went to photobucket and they are not accepting new memberships right now. but i will still keep trying! san wang i'm sooo please those were the seeds you looking for. we absolutely love winter squash! we are enjoying many varieties this year :) happy gardening win

I can't say what's absolutely the best. But what I do is leave them all on the vine until harvest time. For me harvest time is when all leaves are dead, even the newest leaves on the outlying lengths of vines. And the stems are dead. If I notice any that are too immature to ripen on time I cut those off and compost them. I'm always looking for those a month or two before anticipated harvest time. I also don't cut the stem, but rather the vine on each side of the stem. So if I was harvesting some now and some later I might be cutting some critical vines. I have no idea if there is any benefit to this but it was recommended by Amy Goldman in her book "The Compleat Squash". In my garden I'v stopped watering as there are so many fewer leaves and the days are shorter and cooler and vine growth has stopped. The remaining leaves do not wilt so I'm guessing water isn't an issue and I am more concerned with excess moisture in my winter squashes than not enough. And there is certainly some water down in the soil to draw upon.

I don't think this is an issue of harvesting "fully mature squashes". The issue is when they are fully mature. I harvest Butternut when they are completely beige. Long before the vine dies. In fact, there are immature squash on the vine when I do that harvest. Those harvested Butternut last many many months, and the flavor seems good. No question that there is a world of difference compared to a green (immature) Butternut. My summer growing season is long, so the squash are fully beige long before it's time for the vine to die. That may not be the case for more northern gardeners.