Pick two, maximum, chosen by where your buyers actually are: local consumer services → Facebook + Instagram; B2B and professional services → LinkedIn; visual trades (remodeling, detailing, food) → Instagram, with TikTok/YouTube if you'll genuinely make video. Spreading across five platforms at survival-level effort loses to two done consistently. Practitioner guides converge on exactly this.
The honest filter is your capacity, not the platform's potential: every platform 'works' for someone with unlimited content energy. Choose the ones whose native format (photos, video, writing) you can actually sustain weekly.
For most local service businesses, the quiet truth: social is proof-of-life for people who already found you via search or referral. Be present, be real, be recent. And let search and reviews do the customer acquisition.