I was a para sub for several years before becoming a f/t MCPS employee. I really enjoyed it! It was a great opportunity to see what different schools and special ed programs were like. Note that only special ed paras are eligible to get subs! That's important to know I think you can still let the sub office know if you are only interested in subbing for paras. I believe the pay is somewhere around $20 per hour. Subs for teachers make more, but they also have a lot more responsibility.
If you sub in a self-contained classroom (for programs like CAPP, PEP, Autism, preschool DHoH, SCB, or LFI, you'll typically be with at least 1 and sometimes several other paras, plus a teacher. As a sub, they'd usually have me support the least-needy children, and the staff would take care of the ones with more challenges. I found the staff at most schools very kind and nice to work with, but you have to be willing to take direction and not think that you're going to sit there and do nothing. Working in self-contained classrooms, at least in elementary schools, is a physical job.
If you're subbing for other special ed elementary school paras who don't work in self-contained programs, you'll likely be the only para in a general ed classroom with one teacher. You'll be responsible for working with one, a few, or maybe a small group of students. These jobs won't be so physical, but you'll still need to have patience and be willing to take direction from the teacher.
As an elementary para sub, you will likely also have lunch or recess duty, or both, so dress appropriately for the weather. If you're in a self-contained classroom, you'll be helping kids with lunch, even to the point of feeding some of them (SCB and CAPP programs), and for recess you'd be outside with the kids and at least one other para. If you're subbing for a HSM or Focus para, you'll be part of a team of paras who monitor lunch and recess. The lunchrooms can get LOUD, so be prepared for that!
You'll find schools where you really like the people and the vibe, and others you won't care to go to again. If you like the school and the people, give the other paras your contact info so they can contact you directly when they need a sub. Also ask the secretary to put you on their preferred sub list, and they can call you when they need someone. I had three schools that I loved to work at and could have worked almost every day, if I'd chosen to. Good luck, OP! We need subs!!!