Ovulation Test?

Mariah • 25 | Proud mommy of 4 | Wife | Proverbs 3:25
My Doctor currently recommend me to start using ovulation test? I have been TTC for about 8-9 months now. I am 23 & This will be my 3rd child I'm trying for. My other two where not planned so this is all new to me any tips please feel free to comment??