It is getting very tough to decipher an expert from an imposter these days. Sadly, there is no recognized certification or standard in this space - despite the claims, most injectors start treating patients after a weekend course. The best advice is to seek out someone with the highest medical credentials and the most experience. If delegated to a non physician, these procedures are meant to be overseen by an expert physician, who themselves do the procedures as a major part of the practice, and can handle complications should they arise. That would be a dermatologist or plastic surgeon that performs injections themselves, or another physician that has gone through the process to change their scope of practice.
Ask yourself who is going to be there to support you in the rare instance you do have a more serious complication. We have had far too many patients come through our doors looking for support after complications from treatment at other clinics who were incapable of resolving the issues themselves.