Have you looked at it or used it in the last 12 months? No? Sell it or throw it.
Could you replace it for not very much money if you needed to? Yes? Sell it or throw it.
Has it been waiting a long time for a repair? SIOTI.
Was it crucial to your previous pastimes but not to your likely future ones? SIOTI.
Is it particularly bulky for the benefit it brings? (Trombones excepted). SIOTI.
Is it a painting of doubtful quality and authorship? Sell it via the BBC for a stupidly high price.
Does it bring back memories? Keep the best ones/bits and lose the rest.
Is it a tiny piece that you have completely forgotten the purpose of? KEEP IT, on the understanding that you will still not find out what it is for until you can no longer locate it.
Does it belong to someone else? Send it to them as soon as possible. Don't delay.
Is of historical interest, an old Lister, etc? Advertise it.
Is it of high value? Tell me where you keep it.
There must be more...