How to use opks?

Gabriella Marie • ❤ TTC My🌈 . 2AngelBabies #21♍️
Hello ladies (: I've been ttc with my fiance for a year now. & I just wanted some advice on using opks. I just got out of my fertile week (saysGlow) & if I don't get my bfp this month I'm going to try out opks. I have a 28-32 day cycle & really want my first bundle of joy <3 ... anyway I've heard it's best to use twice a day , once in the morning and then in the afternoon . Is that correct does that not work for any of yall ? & both line have to be the same color or the test line a bit darker right ? I just wanna make sure I read everything correctly when I start using them (: baby dust to all ttc ! (: