What are some ideas for Fiverr gigs based on my abilities, and what is the best way to manage code written for such gigs? As in packaging, documentation etc?

Hey guys. I am developing an AWK interpreter and to fund it, I registered on Fiverr to do some gigs. First question is, based on my libre portfolio, can you recommend some gig ideas? I thought about offering FFI for interpreted languages, like Lua/Ruby/Perl/Python C FFI etc but how would I convince people that they need a C foreign function for their project? I have also thought about text-related tasks, I just don't know how to express it you know?

Now what is related to this sub: How would I manage the code written for such gigs? How do I relay the project to the customer, like, what is the best way? As for documentation, what approach do you recommend? Should I overly comment the source code and then generate docs based on those comments like Doxygen?

Besides that, if there's a book about 'management of software gigs', like small gigs, that would be great if you'd recommend it to me.

Thanks a lot.