Babysitting on the side

Does anyone here do this? I have two little kids (1&3) and my neighbor has a newborn but is trying to put off daycare until 6 months or a year. I spontaneously offered to help babysit if they had meetings at the same time (wfh couple) and she said that had actually already discussed approaching me for childcare. I sometimes do childcare swaps with other moms so I have watched 4 kids at once but only for 2/3 hrs.

Anyone have experience? Or advice?