since my cycle is pretty regular, i used mymontlycycles.com to keep track of when i would O.
then we DTD every other day for the week of O.
i think a big thing is to make sure you have the "BIG O"......
i became pg in august last year--i had the BIG O while DTD. i had a m/c in october. then in november we tried and tried, but i was too stressed and didn't have the BIG O---no baby. but, in december, i relaxed, had the BIG O and there was a baby!
i think the important thing for me was to relax and be sure to have the BIG O.
oh, and in november i tested almost as much as Bobbie did

and got nothing but BFNs.
but in december i didn't test until it was time and i got my BFP!
hope this helps!