Basically there your cycle goes
AF, pre ov, fertile upto 5 days before ov, OV, luetal phase, then back to AF again, unless your PG
Most LPs (luetal phases) are 12-16 days, and so you can assume that 12-20days before AF is due you are likely to be fertile, once you've worked out your cycle and know your body better you won't need to guestimate.
There are lots of ways of tracking your fertility, one of the easiest ways to monitor your fertility is your CM (cervical mucus) so from after AF you can check your CM, it can be anything from sticky to creamy to watery etc etc, the fertile stuff is normally EWCM (egg white CM) but can be watery.
Other things you can check but probably won't be necessary are CP(cervical position) BBT (basal body temperature) there's also ferning which I know nothing about, but anything else I've mentioned I can elaborate on, just shout.
People often notice other signs around ovulation, ovulation pains, sore boobs ETC ETC
How long is your cycle