How to figure out the best gaming resolution

I recently got my Surface Book 2 and my resolution is set to 3240 x 2160 and scaling is at 225%.

I have seen different suggestions online, the most common seems to be 1920x1080, and I'm wondering how these are worked out?

I'm just a very casual gamer, but would still like to get the best quality picture.

MrNeeds said:

The best picture quality is the native resolution of the monitor/screen you're using, people only use scaling when icons and the mouse are too small for you to see, if you were to set your resolution to 1920x1080, you'll notice a visible blurring to everything, I myself use a 2560x1440 resolution and I can clearly see a difference between 1080p (1920x1080) and 1440p (2560x1440), the only reason you would need to reduce the resolution is for games that can't run very well at your native resolution, dropping it down to 1080p would be a good compromise.

Oh so I only need to drop it down to games that don't run well at my resolution - got it. I thought I maybe had to drop my resolution down for all games (I only have two games and they offer me the chance to change resolution at the startup screen).

It will always look best for desktop use at it's native resolution.

For gaming use it is compromise, as the higher the resolution the greater are the demands on the CPU and GPU. Thus the game will run at a lower FPS and quality.

Thus lower resolutions are better in terms of Game FPS and Graphics effects qualities.
You should be able to run at 1920 x 1080, and 1366 x 768.

The games will have settings for various Graphics effects some of which maybe pointless and use a lot of CPU/GPU.
That is for you to find out in use, it varies with each game and a users understanding or liking of the various game Graphics effects.