I need help with SEO clients

I don’t know if this has been posted before so I’m sorry if it has.

When I set out to learn SEO, it was always solely to do it for my main website (I never would have imagined that I would have gotten this far, let alone have more than a website).

Although I’m not the most experienced SEO out there, I know a thing or two.

I have been approached by several clients wanting to have SEO done on their websites and it got me thinking that maybe I should offer it; after all, some extra cash wouldn’t hurt.

That said, I have no idea where to start nor how to go about it… I would really appreciate the help and guidance of those that have clients and how you go about it.