I haven't been in three weeks! We've been working around the house, yard, garden and orchard, not to mention work has been busy. I will be out fishing the tournament on Saturday and hope to find several, although I've heard through the grapevine the crappie have been a little tough this week.
With the water warming the pattern will be drastically different depending on where you are at on the lake. As a rule of thumb for April, the warmer the water the shallower the fish. Evenings tend to be better than mornings as the water has all day to warm up a couple of degrees. The closer to the upper ends (Bolivar landing, Pittsburg landing) the shallower the fish should be. The closer to the dam, the deeper they will be due to water temp and water clarity.
I prefer to the main lake this time of year, the fish are deeper which means they are more stable than shallower fish.
Here's my two cents:
Upper end - find the warmest water you can, cast jigs next to any laydown, log, brush, or cover. It does not matter how small the cover is. I like to throw a 1/16th oz jig, white, blue, pink or chart, let it fall slow and real it back slow. The key is to let it fall and bring it in slow. The closer the spawn gets the better white becomes. I'm not much on minnows, however if you want you can dip minnows around shallow structure.
Lower end - fish brush piles in 10-20 feet of water. Look for the piles that are just inside points leading to spawning coves, in front of cuts or in the middle of the coves. The fish are starting to transition preparing for the spawn. In the lower end of any lake the water is deeper and clearer, this means they will spawn deeper than in the upper ends. You will need to fish accordingly to catch these fish. They will also spawn 10-15 days later, of course this will all depend on fronts and storm systems moving through. I prefer to vertical jig with 1/8th oz jig heads. I like using a natural colors such as shad, gray, smoke, white, etc.... and never count out chart!
They can be tricky to find as things change, however when you find them you can generally load the boat.
Good luck!
Brad