Price the work, not only the followers: scripting, shooting, editing, revisions and usage rights all take time.
Build three packages: a single post, a launch pack and a monthly retainer. Brands like choosing between options.
Charge separately for usage rights and exclusivity. Content a brand runs as ads for six months is worth more than one organic post.
Ask for a written contract with deliverables, due dates and payment terms before you start. On Bragni, brands pay you directly through your own gateway.
Raise prices when your calendar fills. Demand is the clearest signal you have.