Easiest Way to Chart
I think the easiest way to chart for pregnancy is by using an online tool like Fertility Friend or something similar. It does a lot of the work for you if you'll just plug in the dates of your period and the days you do the deed.
I have consciously avoided temping and OPKs for the reason of getting wrapped up and obsessed with them, stressing me out, making pregnancy take longer. (For me. I know some women can go about it rather easily with no extra burden of significance to them)
An issue that comes with that is for the longest time I had 'regular' period... except they were regularly about 6 weeks apart. So, my ovulation date is a little off.
Now that I have been pregnant, I am going to avoid charting since I know it CAN happen and stick to my soy isoflavones, EPO, and Fertilitea when we actively try again.