How should a new founder think about pricing those first services?

Most people undercharge. They think in $3 products instead of $2,000 retainers. I like to think in terms of value and client outcome. If you can reliably create content, get leads or grow revenue, charging $1,500–$2,000 a month is very reasonable. Ten of those clients can already put you into multiple six-figures a year without a huge team.