Strategies when selling record collections?

Hi,
I'm right now trying to reduce my record collection. I have a lot of stuff I never play, both junk and more valuable records.
When going through my records it hits me I have some "sub-collections" where I have pretty much/all af the releases from an artist or a label (mostly Swedish stuff)
It took some effort and money back then, trying to complete these mini collections but now some of them are not very interesting to me anymore.
The question is: How do I best get rid of these collections? Are there people willing to pay (good?) for the effort it took me to complete the collections or is it better to try selling the records one by one? (perhaps ending up with some records unsold when the rare ones are gone?).
A collector of a certain artist already have most of the stuff and who else will be interested in going from zero to a complete collection in one deal?
What is your experience?