I am a believer that presentation of the bait is always first. The fall and it's speed can dictate if your going to get fish or not or if you will get dinks all day or not. If you find yourself catching dinks in open water or docks, try to speed up your presentation by adding more weight . One reason that the dinks hit before the large ones (my theory is), that the smaller fish may dominate down there and the smaller ones are quicker to react to just about anything thrown in the school of fish. The larger fish may be below the smaller fish and interested in the bait landing in front of them where they do not have to expend that much energy, especially when the pressure is on either from fronts, colder water, time of the year or activity on the lake.
The fall may be a very subtle change. I have a tendency to go to a larger bait for a faster fall, along with the larger bait I may add a thicker or larger size hook. If this doesn't do it, I slide my weight down towards the bait for a faster fall when I am using a split shot rig. If I know that there is larger fish down there by my sonar, and all of these things did not work I will go to a thinner bait and then step up on the size of the  weight by a 1/16 or an 1/8th. The thinner bait will not scare the fish away as fast as a larger bait may. Plus, if the water is colder or they are pressured, a thinner bait may do the trick where keeping a longer size may entice the larger fish. But the bait will fall faster, through the small ones, and right into the larger fish.

If you know you have tried your hardest with presentation, size and types of baits then it is time to go for the color. Everyone has a favorite color and there are always those special colors or a shade of those special colors that will always work well anywhere in the world, such as Black/blue, or as an example of shades or hues try smoke/blue fleck for clearer water. Red shad always works or tequilla sunrise may work better in deeper water. Plain black is another color that will work anywhere, as well as junebugs with the black grape.

But lets say you are going to a strange lake and you know nothing of this lake. I am going to carry the colors listed above. Then the very first color I will throw will be the color that will match the water. In clear water on sunny days, I go to brighter colors with lots of fleck. The flecks I try to match the forage and baitfish that are condusive to the lake. A laminate with translucent colors such as watermelon seeds, motor oil/green fleck, chartreuse/ black flecks or clear with blue/ purple or blue flecks, silvers, bubblegums or whites works well. 

In clear water on cloudy days, blues or Junebug is a good color. Rootbeer which is basically like pumpkinseed but has more translucents, is also good. Go with more translucent colors with no flecks or solid bright colors as well. Watermelonseed and rootbeer again will always be my top for this condition, due to the fact that the sun will make the forage bright green and brown when the weeds start to die.

In Tea stained water on clear days, browns such as root beer or Pumpkinseed would be my favorite, again the colored flecks should match the baitfish.

In Tea stained water on cloudy days the bright translucent colors are good but only with another color(laminated) for example, in Pumpkinseed/chartreuse. This shows a natural color with an eye catching color that can look like the flash of a baitfish. The backs of baitfish are dark with the middle of the body and bottom brightly colored. Solid colors start to work here as well, such as a green pumpkinseed.

In muddy conditions- always use a natural or nightcrawler colors, pumpkinseeds, blacks and dark blues such as junebug. On the brighter days bubblegum or pearl white may trigger a strike.
Again, I always carry the colors that work everywhere and I go by these rules that I have found to work for me with time on the water. I also try to match the creatures that may live on the bottom such in rocks I will go to shad colors such as grey and watermelons for the moss. The reason I match the bottom is that the creatures will often camoflage themselves to thier terrain, but when there are rocks I always go to laminated baits where crawfish live and the crawfish have two tones when changing colors for camoflage.
For shallow water I will match creatures with green and yellows to match frogs, and bumble bees with blacks and yellows. But for the weeds and pads these can be reactive colors as well, but for some reason when all else fails, black and blue always seems to work for me in shallow water with pads. A bass sees different than we do, who knows why it works, but it does for me. 

 
The red is said to be a triggering color for blood or gills, and this may be so, but I can tell you that the red flecks work for me in certain colors such as blacks and watermelon and green pumpkins, as well as motor oil and root beer. Anything else with red flecks do not work for me.

This is my take on colors. I spend an awful amount of time on the water and as far as plastics go, this is what works for me. Give it a chance and I hope it will work for you as well.
Bearpaw