What I learned from a friend who is a pro photographer is to make multiple passes. I'll try to do a quick one when I import into Lightroom to cull out unfocused or unsaveable images. Then I'll go through and cut out shots that are basically duplicates.[1] Then I'll go through and see which ones I want to develop further in Nik/Lr/Ps/etc. and star them.
Then I'm a battle royale optometrist, doing "a or b" an killing the weaker candidates.
Just getting in the habit of killing (or, at least cropping out the junk) the photos that you won't care about in the future is a good start. If you're looking at older photos and wondering "why did I take that," delete it right then. You don't have to have a clean desk right away, just shred the paper you don't need when it gets in your way.
[1] I've gotten into wildlife photography, so I often have a burst of ten shots of a bird in flight to get one that is really special.
Oh yes, I do that to a fault. That is, even of something static I will take at least 5-10 shots at least, just to get the one where the autofocus hit the nail on the head, and especially with hand held shots in low light. Multiply that for living things, which means hunting for the combination of good crop/focus and situation.
I am not pro by any means, but I am "vicious" about selecting and editing simply because it makes photography so much more fun for me, and the results pleasing to myself. It makes me feel okay instead of bad about the glass I bought, too ^^ I don't mind going back to old photos and changing tweaking the RAW conversion parameters either, and this way I don't have to obsess too much about getting it just perfect on the first go (because as you know, when you stare for too long at a specific set of things, you loose perspective, I find it rather more productive to step away from and then revisit things, but of course that's a luxury of not doing it professionally!).
So, I try to keep only 36 or 72 around, thinking of them as rolls of film. Unlike a roll of film that you brought back from vacation that only had a couple decent photos, these "virtual" rolls have 36 of your best shots.
You are not actually killing that person, or destroying that object; you are just deciding which one(s) of the photos of that moment or mood capture it best, and delete the ones which are just slightly worse variations of those.
It takes time though, that is a real cost. Though I think that time is made up for down the road, when you don't have to wade past the photos you deleted, or wait for them to upload/download/backup, etc... even a little bit of self-discipline adds up to quite a bit over a lifetime of digital photography. I think of it as removing weed so the flowers are more enjoyable, and have a greater probability of actually being seen (photographs are kinda useless when they are not seen other than by the bulge they create in the pagination; flickr is like a graveyard where good photos go to get overlooked in that way).
I've been doing this for a about 5-6 years now, so about 3 years ago I started deleting the raw shots a few months after having finished the film. To date I have not once regretted deleting a photo.
This doesn't fix the problem though. A tool to coalesce multiple sources and allow for easy sorting/editing with a way to them publish that result is really key here.