I took coq10, vitamin D, calcium, and baby aspirin in addition to a prenatal with methyl folate. I got pregnant the month I started the baby aspirin and prenatal with methyl folate (previously took one without, discovered I have double MTHFR variant). I had been trying 9-10 months with one early loss.
These are the vitamins that I deemed fairly safe and uncontroversial. A lot of OBs don’t recommend anything because they aren’t experts in this area. If you aren’t pregnant in a year, they just move you on to the fertility docs.