What to keep?

I'm taking stock of what I have in the house and trying to decide what to keep and what to toss. I think I'm the kind of person that likes to save stuff "just in case." I have a hard time getting rid of things that are useful, even if I haven't used them in months...or ever!

This house, while quite large, doesn't have a lot of storage space on the main liveable levels. Three out of the four bedrooms have small closets, and the biggest one is not completely useable because the plaster is coming off the walls in it and needs renovation. I don't have a linen cupboard. The main floor has one coat closet, and another closet under the stairs, aka, the "Harry Potter cupboard."

The basement is a mix of finished and unfinished. The main finished area is just a big storage area at the moment. We don't have any utility shelves, so things are just piled and stacked everywhere. I'd really like to be a little more organized down there, but I think part of the problem is there is just too much stuff.

What should I do with stuff like this?

• Original boxes for china, glassware and other breakables
• A bunch of different sized cardboard boxes that could come in handy for storage or mailing parcels
• Boxes of bubble wrap and packing paper 
• Good quality plastic bags (shopping bags from nice stores)
• Lots of washed, reused ziploc bags 
• Glass jars from food products (honey, pasta sauce, applesauce) that aren't canning quality  
• More mugs than we can use
• Corelle cooking/serving dishes still in the box (but I really like the look of them!) 
• Old issues of Kraft and other cooking magazines (there might be a recipe or two in them that I've used), decorating magazines
• Hair products that I haven't used in a couple years but might need again - hairspray, mousse, special conditioners 
• Extra bedding and curtains given to me that are not really my style (but might come in handy for lots of extra visitors)
• Knick-knacks with some sentimental value or that have been passed on by someone I know, but that don't really get put out because they are not my style or there are just too many of them

Is it worth keeping these things because it might cost me down the road to replace them? Or is it better to free up space (physical and mental) and toss/recycle/donate? 

~lg