The dreaded D word... Discount
A discount percentage is only part of the decision.
I think this is an important topic to cover on the Backbox that is Steam.

Which Steam Discounts Notify Wishlisters?
If you skip over the rest of article, only read this nugget here:
In order for wishlist players to be notified; Steam's wishlist documentation specifies:
- A discount of at least 20%,
- Affecting the lowest-priced package
- Lasting more than eight hours (A single day)
That means discounting only a more expensive deluxe package is not equivalent to discounting the entry package.
Check whether the discount itself is allowed
Valve's discounting rules describe 30-day restrictions after release, price increases and other discounts, with specific exceptions. Seasonal sales do not remove release or price-increase cooldowns. A launch discount must be configured before release - 20% is the golden standard here.
How to maximize that discount
Include a news post with your discount as this sees better conversion. It might be due to activity on the page. Upvotes and comments all factor into the visibility algorithm. Combine that with a sale and your increase your exposure potential.
A hesitant buyer may have been waiting for price, a particular feature or evidence that a reported problem was fixed. A promotion works better as communication when it addresses a real reason to reconsider.
Before a deep discount, run a basic revenue thought experiment
Let's not race to the bottom on discounts, I think you shouldn't exceed your base discount for at least 6 months after launch and then cap it at base+10% for the rest of the year. The following year you can reduce that by a further 5% and so on... fast drops in price can negatively influence your game as well.
Selling 100 copies at 20 produces the same gross amount as 125 copies at 16. So you need to sell more! Don't discount for the sake of discounting.
Get your marketing materials (Steam page, videos etc) in order first.
Prepare, prepare, prepare
Before you lock in the discount, check that the description, screenshots and video explain the game - you can update these at any time to reflect changes. Oh, and here is the most important Discount tip - Be sure to Stream a broadcast to your game page. Use OBS or Broadcastloop for the period leading up to your sale, but also a day or afterwards to capture residual traffic.
Visit any AAA game on Steam and they are broadcasting over a discount period - WHY? Because it works.
BroadcastLoop can help!