Fish as heavy a head as you can get bit on. Sometimes for me I get bit better on a smaller head....so I just pinch on as heavy a split shot as I need a couple ft up the line. You can also use a dropper rig with a sinker on bottom and a couple dropper loops coming off,heck sometimes people use as heavy as a 3/4 oz sinker or so on a dropper rig. Or a heavy jig on bottom and a lighter jig above it. Or a jig on bottom and live minnow above. Or a drop shot rig.
Just don't soak something for long if it ain't gettin bit....try something else. Sometimes things work good only for a while then fish are looking for something else. You can wail on fish for a month sometimes with a rig... then bam they want something else. Some bodies of water some stuff works better than others...and I do not know why...they just do.
And you can back off and cast and countdown sometimes don't always have to be vertical.Sometimes that slow falling bait is just what those fish want to see.