I used to own a cleaning agency.
Points to think of:
Going rates in the area (I charged £14ph but that was an agency, and £10 went to cleaner)
Insurance
Will you use your own products or have householders provide them - if you use yours, you need to make sure you don’t cross contaminate your cloths.
Advertising - gumtree and rated people were gold minds in my area. Word of mouth is brill too - I offered a discount if someone recommended me to a friend.
It’s hard physical work, but easy to build up a routine. Oh! And Fridays / Mondays are most popular days, so if someone isn’t bothered about which day you come then put them midweek and save those slots for people who aren’t flexible on days.
Lastly, as a general rule of thumb (not a given so don’t take this as law!) I would expect 3 bed house = 3 hours weekly, 4 bed = 4 hours etc. If fortnightly wanted, then add on an extra hour as you will have more build up over that time.
Any questions just yell and I’ll be happy to try help :)