Consider Popular traps to use, for example "Fiendish Chain", that you could potentially set off at a bad time for your opponent, in "Fiendish Chain's" case you could set it off while you have small, harmless monsters out, making your opponent waste their trap.
You can potentially use 1 Bait Doll in your deck since it goes back to your deck instead of graveyard after it is activated, so it is reusable.
Use this card in combination with Jinzo to destroy face-down trap cards without fail.
Use this card with Chain Burst to force your opponent to take damage for activating their trap.
This card is useful in a Spell Counter Deck because it returns to the deck instead of being sent to the graveyard.
Set your own Spell Card to always have a target for this card.
This card can be used to prevent decking out. While you have no cards in your deck, but this card in your hand, you can set 1 spell card, and activate Bait Doll, targeting the card you just set. Since it is a spell card, it will not be activated, and will be set again, and Bait Doll will be shuffled back into your deck. Next turn, since bait doll is the only card in your deck, you will draw it, and can activate it again, once again, targeting your set spell card. Repeat this process each turn, and it will be almost impossible to deck out.
Since the target trap is activated as part of the resolution of "Bait Doll's" effect, counter traps and most negating effects cannot be used to prevent the target's successful resolution. As such, you can use Bait Doll on your own traps to ensure that your opponent can't stop them without first negating the Bait Doll itself.
remember not to use "Bait Doll" on your traps that were set this turn.
if you target a trap card that was set this turn, then "Bait Doll" will always destroy it. this is because traps can not be activated the turn they are set (thus the activation timing is not correct.)
you can not use "Bait Doll" to forcibly activate your traps that were set this turn. rather, they will be destroyed
if your opponent sets a card on your turn (i.e. with "Dust Tornado") you can destroy it without fail (assuming it is a trap)