I have ventured into this with very little success. I do kill dots with a dotting brush, and thats about it. One thing I did try that hasn't worked yet, is called "inking" in the figurine world. It will only work on textured areas of baits, but I'll throw out the process so you guys can think about it.
Paint your bait normally with acrylics, then either brush or dip on a coat of future. Take oil based artists paints, that contrast the colors of the bait, maybe red for gill areas, black for lighter areas, etc. and thin a ton with fake turpentine. You want the paint to flow just like water. Now, load a fine tipped brush, and place the tip in a crevice that you want highlighted. The paint will flow into the crevice and coat the entire area. Use a tissue to clean up goofs if there are any. To get really noticeable highlights, this process should be repeated a few times.
Now, as I said, I have tried this on cranks with no real success visually. I use it on airplane models to make the panels stick out and it works great. I think my problem has been that the colors were too similar, but I haven't given up on it yet.
Zack