I am also relatively new to list building and I just want to post a quick tip that has helped me boost confirmation rates significantly:
After entering their email, send your prospects to a "thank you" page that has clear instructions and a screenshot of how to spot your confirmation email in their inbox and click the link inside.
This method dramatically increases confirmation rates, I've been testing on a few of my campaigns and have seen up to 2x higher confirmations.
I used to send new prospects from the squeeze page to an OTO page, but noticed that they were not buying, and what's worse, very few completed the double opt-in. By giving them clear instruction and a call to action, this changed. I now send to the OTO upon confirmation and even if they don't buy, they're on the list so I get a 2nd chance.
Happy list building!