By definition, acorn squash is a storage crop meaning that if you store it properly, you can keep it for months! They like a cool, dry place with good airflow and lack of sunlight. Check it regularly for signs of softness, mold or wrinkles; if you notice those developing early, you can easily save most of it by preparing the squash promptly and cutting out the soft parts.
The way we prefer to prepare acorn squash:
Both the roasted squash flesh and seeds can be used in a variety of dishes, or great just eaten as a snack!
New Whole Foods Encyclopedia by Rebecca Wood
From Asparagus to Zucchini: A Guide to Cooking Farm-Fresh Food By Fairshare Coalition
Produce: A Fruit and Vegetable Lover's Guide by Bruce Beck
Our own experience!