It is a good idea always to check how you can get to your customer (by bus, train, bike etc.) so you won't arrive late. The day before the cleaning, look up the address and transportation on ex. google maps. Remember to check public transportation updates for any delays.
At the first booking with a new customer, it is a good idea to talk about what the customer expect so you know where to give a little extra. Ask if they have any areas they want you to prioritize or if any surfaces requires special soap.
If the customer doesn't have any further comments then we advise you to follow the instructions in the cleaning video you can watch here https://www.youtube.com/watch?v=CCwG4B8vbUk&t=28s.
The customers can get a tax deduction, since the cleaning can be considered as an "improvement" of their home. For this they will need your CPR number to report the cleaning to SKAT. Therefore, it is important that you are willing to give your CPR number to them if they ask.