Not sure if this helps but I found this regarding vitamins to take when ttc: https://www.thebump.com/a/vitamins-you-need-to-conceive
Maybe you could look up foods that contain high levels of those vitamins and try to eat as many of those as possible. As to what to avoid, as the pp said caffein is a big one. That really is hard for me because I love drinking black tea and I also use caffein sometimes to take away migraines that I'm prone to getting during my cycle. You probably already know this but alcohol, smoking and over the counter drugs such as ibuprofen and high dose aspirin should be avoided. Low dose aspirin can be taken (up to 81 mg per day), in fact I've read that taking low dose aspirin once a day while you're ttc can help build uterine lining. Try to watch how much sugar you consume as well to avoid gestational diabetes when you do become pregnant.