How Can I Start a New Routine For My Baby, Toddler Without Any Crying?

I frequently get phone calls from sleep deprived parents asking for my help, explaining the routine they are currently using and what they would like to achieve with the new routine and then they add.... "But, I don't want any crying...my husband and I don't cope with it". I completely understand this request and my aim is to empower the parents with the skills to improve their baby/toddlers routine without any crying or distress and sometimes this happens at the first sleep but sometimes this isn't possible for good reason.