OPKs? Which do you prefer? What do I Need to Know?

So

Ok, so I'm starting TTC cycle #2 and with cycle #1 I TOTALLY missed my ovulation. This month I'm planning on using CM, BBT, and OPKs to try to be more accurate. But I really have no idea what I'm doing. What OPKs do you all prefer? And what do you wish someone had told you about OPKs before you stared using them?