How often to have sex?

I want to know what is the best method when trying to conceive.... Having sex everyday or every other day because I have heard both sides to the debate and I don't know when to time it during my ovulation window....one of my friends  got pregnant the first time they tried and she told me they had sex every day during that whole month and even sometimes twice a day!! I know everybody is different but I just need some insight on this....