I didn't see you list a trimmer. probably need one of those. For me, to use a straight riding mower, would be a waste of money and time. Depending on your finances, i would go with a walk behind. (hydro) Versatility!
For me , most of the residential yards i do are between 25-35 bucks. thats edging, trimming, and blowing included in the mow. I would probably never do a yard for less than $25. 20 bucks if it was super small.
If you are doing residential lawns, Just offer anything else that you know how to do. Tree/shrub trimming/removal, planting, fertilizing, mulching, seeding, general cleanup.
I don't know hardly anything,but one thing I do is ask alot of questions and I'm always searching for answers. Good luck to you this year!