Something I'd like to add:
When you've sold something on the AH... remake it. For instance, I sold 2x of a certain glyph, then 2x of another glyph and so on. I don't just cancel/repost glyphs until they all sell, I continually remake glyphs (when I am online, rescan AH for highest selling glyphs etc) even when I still have 100+ glyphs unsold.
If you don't have much gold (at the moment) but you still spend gold frequently it might not be the best choice to remake glyphs/gems/enchants as soon as they sell. However, if you do have a decent amount of gold at the moment PLEASE do yourself a favor and reinvest your earnings into making more glyphs/gems/enchants etc. Your gold will pile up immensely.
For the sake of argument lets categorize glyphs into popular and unpopular. Now let's say that all of your popular glyphs sold and you still have unpopular glyphs left. I guarantee you made profit from the popular glyphs alone so now all you did was create an inventory therefore you don't continue to make unpopular glyphs when you have an inventory (inventory=unpopular). You "try" to get rid of your inventory (unpopular glyphs) by simply cancel/reposting them as you go but your main focus is making new (high selling, high priced) glyphs that are more than likely going to sell.
Stay rich my friends