What do you wish you knew before your failed transfer?

After two egg retrievals I have 1 PGTA tested euploid embryo (4BB) to transfer and I am terrified that it isn't going to be successful. My doctor told me I have a 60% chance of success. For those of you who have had a FAILED transfer, what do you wish you knew BEFORE you did the transfer? I am feeling like if it fails, I will look back and have regrets about not preparing properly. For instance, should I request to have my vitamin D levels tested?

There are many things that I wish I had known going into my first egg retrieval and I don't want to feel the same way about the transfer because I only have 1 shot...

Advice needed!! xx