When learning how to drift fish, make sure you know what each type of bottom structure feels like when your leads taping bottom. So when there's any uncertain variation you can lay into em'! When using bait, the pickup may be an erratic tap.tap.tap like a small trout, or a slow tap or headshake, or they will simply pick up the offering not really telegraphing a bite.

If your not really sure if a fish has picked up your offering or its a rock, take a couple turns on your reel instead of snapping back hard. This will not distrupt the rest of your dirft and if it IS a fish you have set the tip of the hook and any further action from the fish will sink it home.
_________________________
"I have a fair idea of what to expect from the river, and usually, because I fish it that way, the river gives me approximately what I expect of it. But sooner or later something always comes up to change the set of my ways..."
- Roderick Haig-Brown