New to ttc

Yesterday me and my fiancé of 3 years have decided to try and we are very new to it. We started trying last night which I just got off my period the day before so I understand the chances are low in my cycle right now but I need some tips from you ladies. How often do you have sex ? Should I be taking any vitamins? My cycle is mostly regular but for a while it’s been becoming irregular coming way late or way early or iv been skipping months so how do I deal with this? Should I go ahead and try tracking ovulation ? I need all the information I can get. Thanks in advanced:)