Another point to remember always is that you are fishing for inactive fish.  There are some principles that always hold true when angling for inactive fish.  First you must keep your presentations very slow.  A jig combo that is retrieved fast will not likely enjoy much success in these conditions.
 
You also need to scale down your tackle when fishing for inactive fish.  Actively feeding fish may ignore heavy line when deciding to slam into one of your offerings.  Crappie is the middle of summer will be much more aware of their surroundings however.  The smart angler will use invisible fluorocarbon line of a four pound weight class.  He will also scale his jig size down and make a slow presentation.
 
I stress enough how important it is to use a high quality light action rod when angling for summer Crappie.  Quite often these fish will pick up a bait in their mouths and hold it there for awhile before committing to eat it.  This is much unlike their behavior in spring and fall.  It is very important to your success on the water for you to have the ability to recognize when a pickup has occurred and set the hook before the target fish drops your offering without you ever having known he was there.
 
This is in a nutshell summer Crappie fishing.  It can often be an all or nothing affair that yields a huge live well full of fish one day and an empty stringer the next.  By following a few simple principles however you can assure the former happens more often than the latter.

To get the full "Why Summer Crappie Fishing Is Completely Different - And How To Adjust" article you'll need to download it here.