Nicky:

A friend of mine – your average pack rat by genetics – got religion a few years ago, regarding his shop: some of his rules -
Stationery Tools – if I haven’t used it it two years, sell it!
Hand Power Tools – if I haven’t used it this past year, sell it!
Scrap: if I can immediately think of what I’d use it for, get rid of it.
Things on horizontal surfaces: If it predates my last project, put it away (really, away; as in “in or under” something) – if I don’t have room in or under something; something has to be thrown out).
Dirt – vacuum at the end of each day; blow-down the shop with a leaf blower at least once per week – whether it needs it or not.

I’m sure there are exceptions and other rules, the ones above make sense to me; but you have to be ever-vigilant and execute.
MJCD