There are several online critique groups. My personal recommendation would be Critters which is well run, produces good critique, is focused on being positive and diplomatic, and is free. They also have a mechanism for getting feedback for longer work, such as novel length pieces, called a Request for Dedicated Readers (RFDR) which most sites can't deal with.
It is a truth that it is easier to see someone else's mistakes than your own, but you will find yourself pointing something out to someone and then thinking, "Hang on, I do that." It's a great way to learn and it doesn't require a physical meeting or venue, which can sometimes be difficult to organise and can fit around shift patterns or other commitments. You do have to set a reasonable amount of time every week to do it, though. An hour or two should be fine for most weeks.
Another way to edit is to work through the paragraphs backwards. This prevents you being caught up in the narrative flow and forces you to consider each paragraph as a stand-alone fragment of story. It can help you to tighten your style and pick up things you would otherwise miss, but it won't help with the character or story logic issues that KatG was mentioning.