I think you should build a super simple chat client or use something like whatsapp and integrate it into a browser. That way, a potential client can find you and immediately engage with you about their needs. This is frictionless. Someone can type in real time and then book them. You can use asynchronous tools like email or a video chat like appear.in.

You should prob consult/explain for 5 minutes free and then make your rates known. After 5 minutes have them do a quick stripe payment, and then run a meter. Something like this is quick, frictionless and unsophisticated. You could even put the price on the screen like a taxi meter but this could actually be negative. Transparency works tp a point though.