OPKs - never used them and don't know if I want to. With the last two children we pretty much got down to it every day and fell first month both times. I realise thought that was 10 years ago though and things probably won't be as simple now.
Most month I usually get a twinge and lots of EWCM at around CD8-10 anyway and am pretty regular (26-28 day cycle).
Give it a couple of months and see how you get on before becoming too analytical about it all? They are super-easy to use, just pee in a cup and dip, same as cheap preg tests, and v easy if you have regular cycles, but are (possibly) a little harder to interpret, as the intensity of the line is meaningful (i.e. a faint pos is not a pos for an OPK). I use cheap ones from ebay/amazon, I think the brand is one step, they are fine. But unless you have reason to, give just having plenty of sex a go before you go scientific.