Product Hunt is still a great source of traffic for new (or reworked!) products. While it won't make or break your idea, it does help generate momentum and awareness. Here are some tips I've picked up from my recent launch.

What worked

1. Build in public - Weeks before the launch I documented everything I was doing on Twitter. This helped build up an audience that was "primed" to upvote when the launch went live.
2. Get early upvotes - Product Hunt starts its 24 hour clock at midnight PST. And your first hour is important in getting to the front page. Ask a friend to help promote when it goes live. Don't stay up late - you want to be active during the day!
3. Live tweet - Tweet in the morning that you launched and continue to update the thread throughout the day. Talk about big wins (visits, sign ups, sales, etc.) and interesting comments. The more you comment on the thread the more it will re-appear in folks' newsfeeds.
4. Be genuine - Don't ask for upvotes (or comments), ask for support. You're probably nervous, let folks know! I found this helps folks resonate with why I'm promoting the launch. They will want the same in return when they go live.

What didn't work

1. Day-of e-mail campaigns - Unless you have a huge number of subscribers this won't be worth it. Think of it this way: if you have 1000 subscribers, 10% click through, and 10% of those upvote you only looking at a single upvote.
2. Twitter ads - I spent $15 and received 2 clicks. Crazy! If I was linking directly to a paid service $7.50 CPA might be worth it, but not for fake internet points.
3. Obsessively refresh metrics - This doesn't help anyone. If the numbers change you get a small dopamine rush. But when they don't the "down" is worse than the "high" - stick to checking on regular intervals (e.g. every hour).

(BONUS) What could have worked

1. Post to Indie Hackers - A great community that offers a ton of support to public launched. Somehow this missed my radar and I totally forgot. Don't make the same mistake!
2. Get hunted - I couldn't find someone "important" to hunt my product in time. Maybe it would have made a difference in the beginning, but I can't say for sure. My advice is that if you can do it, well, it can't hurt.

P.S. I'm Joe Masilotti, I blog about this kind of stuff on Masilotti.com. The product I launched is Mugshot Bot. Cheers!