Opks... Wth? Super confused

My fiance and I are TTC... With my first child it was me accident that I got pregnant but now 6yrs later, we have decided to actually try for a baby. However, it seems impossible to figure it all out. I have a very irregular cycle ranging from 28-70 days, even my periods last different lengths of time. I want to try ovulation tests but Idk when to use them, especially being irregular. Is there a better time of the day? Should I test several times a day? Should I test on a certain cycle day or just text every day? Any advice would be great!