Sometimes the best line of attack is to remove EVERYTHING from the drawer or rod and start from scratch. When everything is cleared out, it only takes a moment to give the emptied space a quick vacuum or wipe, then a nice, clean place to put back only the BEST stuff.
Be HONEST about what should go back so that the wardrobe is full of good feelings.
Is this in the right place?
Does it fit?
Is it flattering?
Is it out of date?
Has it seen better days? (Is it worth repairing?)
When is the last time I wore it?
Do I like it?
Another thing to keep in mind its whether your lifestyle has had any significant changes. For example: when I changed from the full-time professional office environment to a freelance-from-home work life, it took me YEARS to admit that I only needed enough slacks and blazers for the very occasional meeting instead of every day. As a result I was able to purge all but the VERY BEST of this category of professional clothes and give the rest away. Now when I do have a meeting it's very easy to put together a nice outfit and I freed up a significant amount of closet space. Moving to a different climate would be a similar opportunity to purge.
Today's small victory:
And from my youngest son's shirt drawer:
some are rags, most are off to another family