I understand your concern. The truth is that both are important!
But of course, you have to avoid cancellations! Cancelations, delivering late and responding with delate to new customers that are requesting information, it is not good ! You have to avoid it as much as you can !
Although if you maintain your level of response rate, Order completion, and Delivery on time, and do not cancel more for a while, you will raise your ratings again!
However, the negative review will always be there.
My advice to you, is that always, before accepting an order, talk to the customer! Analyze how he treats you, how he talks to you. If it is very demanding. And If you see that this client can give you problems, or is been rude to you, just do not accept the order!
Be always nice with them, and show them you want to help in anything they may need !
And of course ! Always deliver a “Excelent work”
If you have to work more hours to keep that client happy I would do it ! And after that, you can chosse not to work for this client again ! But like this you avoid bad reviews ! and bad ratings !
Always keep the client happy !
Also, the comunication is the most important ! Once you have accepted the order, if the client wants to make it difficult for you, he/she, will.
Try to be as kind as you can always, and be patient. There are customers who believe that for $ 5 they can have whatever they want, and make you work hours and hours!
And I insist, sellers have to use psychology, and make sure as much as possible, with whom we are going to work before we beguin to work for them!
I hope I’ve helped !