I always prefer to use a small local business rather than a big chain or franchise if at all possible. Ask around, among 'real' people rather than your local FB page, and get some recommendations.
When you do find a suitable person, feel free to ask to see their insurance certificate, and make sure you talk about things like holidays, bank holidays, what happens if cleaner is sick.
Also write out a check list of what you expect to be done. Not just 'clean bathroom' but 'clean bath, shower, basin, lavatory, including outside of bowl, wipe down tiles, dust windowsills and skirting boards, sweep and mop floor'. Discuss what products will be used and decide if you will provide or cleaner. Ditto mops, cloths and vacuum cleaner.
One thing that can cause seething resentment is leaving an area that's due to be cleaned really untidy. On cleaning day, at least ensure the kitchen work surfaces and sink are clear of unwashed up dishes. Most cleaners won't mind a couple of mugs and plates left after breakfast, but an entire mountain of leftover stuff from last night's supper is a bit unfair!