+1 fishdevil.... Anytime the water falls below 75 degree's (from my experiences) thats when they seem to do a little better (I like around 53-60). Most all of my bigger fish have came off a jig/plastic combo. I personally use a glass rattle on my jigs, but I think thats mostly a confidence thing for me.
I also use a jig type with a narrower head in or around rocks, grass, and real heavy cover (I feel I get hung up a little less,) and the Football style when fishing small gravel bars and points with sparse cover. The football type let the trailers stand more upright, and sometimes that can be the ticket. Generally a 3/8 oz., but lately I have been using the 5/16 Finesse Round Head with some pretty good success.
You also might want to try and trim the skirt length down sometimes to match the size of the available forage. Most larger jigs (3/8 and up) have a pretty good amount of skirt, and sometimes if you cut them down it increases your bite ratio. That was the main reason for me switching to the 5/16 oz. finesse lately...... Seems to have helped.
I also trim down the weedgaurd to a 45 degree slant. This will still allow for a weedles jig, but also increases you hook-up ratio by allowing the hook to penetrate a little easier.
Vary your Jig trailer style as well. Sometimes I have had a real slow day by using a "straight" tail type trailer (Zoom Chunks) then turned my day around by switching to a "swimming" type trailer.
I also try to use as silent an entry into the water/cover as I can. I tend to pitch alot as this seems to suit me style better. I think it increases my odds if the bait makes alot less splash.