starting out as a tour guide looking for tips from experienced guides how to sell tours online

hi everyone! i am 28 and have spent last few years working as a guide at historic sites in lisbon, portugal, helping school groups and tourists explore the city. recently, i got my national tour guide license and want to start full time, running half day cultural walking tours and maybe themed food or small group tours.

my sister and i plan to do this together we share the same vision, motivate each other and brainstorm ideas as a team.

i would love advice from experienced guides:

which booking platforms work best tripadvisor, getyourguide, airbnb experiences, etc.?

unexpected costs or lessons you wish you knew when starting?

thanks in advance for sharing your experience!