I wasn't sure where to put this, so I apologise if it's in the wrong section. This is a little tip I came across a year or so ago whilst editing. I found - as stupid as this sounds - that changing the font before editing actually helps me spot more mistakes and awkward wording. I suppose it's the same concept as printing your work out before reading through it. I'm not sure why exactly it helps, but it does. For example, I wrote my work in Times New Roman and changed it to Courier when I printed it out. I guess it helps because it alernates from what you're used to, so you automatically read with more care.