Hi tascha,
-my natural bfp was a fluke, we had only been trying for 1 month and i had only a vague idea that I O'd around day 11/12, we DTD on CD11.
-my most successful bfp ( as in, we got to see an embryo with a heartbeat @ 7 Wks before m/c) was an FET, the things i did differently from other ivf transfers were; cut sugar out of my diet for a few months prior, DIDN'T do a pre and post transfer acupuncture ( time and location issues prevented it) and like Tei, my DH wasn't present at the transfer, so as you can see theres no rhyme or reason.
I'm still a fan of acupuncture though lol
Best of luck
p.s. My DH's colleague and his wife are having trouble conceiving, his advice to him "whatever you do, don't tell her to relax" ....he learnt that a long time ago