without charting & temping, you could try OPK's, and/or watching your CM, but those just let you know your body is about to ovulate, but that helps too since the sperm can live for up to 5 days I think and the egg lives up to 24 hrs so bd'ing when you think you are about to O is easier timing than trying to pinpoint exactly when you O.
Some women get cramps and/or twinges when they O. I either never had them before the 1st pg or I just never noticed them until I started looking for signs
Good luck!!