I agree with Peckish. Lots of folks ask for lots of stuff (lessons, custom quilt etc.) but when they have to put their money where their mouth is, they loose interest. I personally would want to do one-on-one (or two) in my home. Since you have already had a business, you know the ramifications of using your home for business purposes & what insurance you would need (for when a student sews thru their finger). I'd want a very small group because they will probably bring their own machines and if they are looking for a beginner class, they don't know how to operate it, so you are going to have to figure it out & every brand has their own quirks. I would also make it project based and you are going to want at least 2 hours to actually accomplish something in any lesson. Depending on the item you are making, I would provide the student with a list of tools they need and also a list of materials for that project.