If you need fast feedback
Start with Search. It forces clarity (keywords + intent) and usually exposes weak promises quickly.
If you need creative exploration
Start with Social. It helps you test hooks, positioning angles, and short-form benefits.
If you need retention and education
Start with Email. It reveals whether your story holds up beyond a single ad.
Rule of thumb
Pick one channel first, polish it, then expand. Multi-channel too early increases noise and token spend.