Hello beautiful members of NextGenUpdate, I'm compiling a list of good places to go checkout for steam sales. If you have any other reccomendations post them in so we can add this up to help each other.

1. Steam Sales Tracker:
You must login or register to view this content.
I personally go here quite often, they have it split up between Daily, Weekly, etc.. sales so you know how long you have to get a game. They tell you the percent off + the original price and even have the reviews with it. Have an extension for your browser and you can also login with your steam account so they can highlight games you already own and create your own wishlist for ease of access. Very good place to go in my honest opinion.

2. Steam Sales Reddit
You must login or register to view this content.
Another Place I often visit, has the same information as SST(Steam Sales Tracker) but, you can also get the feedback from other reddit users that have recently purchased the game. Get real insight on what they personally think (The Pros and Cons).

That's all I have for now, leave some recommendations of other places to look.