The day after PH launch... what's the best thing to do?

Keep your new users engaged. Try to reconnect with them as soon as possible. Collecting e-mails or simplifying your sign up page could potentially retain a large portion of PH traffic. In my case, I created a 1 click sign up button w Twitter so the chance to acquire a new user is higher than a normal sign up page. Also, I recommend you to post your PH Launch in your product site so any traffic that comes from any other platform can potentially give you some extra upvotes. I believe after 2 days PH sends a newsletter with the previous launched products, and those extra votes can help you to rank a little bit in the newsletter. So more visits for your site and potentially new clients. No need to do any extra work, just keep updating your new user base with the features you're working on and when you plan to release them. Remember you can always launch the same product in a new version (like 2.0 or 3.0) so take your first launch as an experiment and don't be afraid of failure.

1. Eat well 2. Drink well 3. Sleep well