How to make things right starting a new project

Hello guys, Can you please help me to understand, which window size should I use in the project.

My phone has 1280×720, so should I start a project with same size? - The question "why" is because, I want to work with 16:9 ratio and I want my Sprites looks sharp and clean and if my project for example is 640x360 (also 16:9) OR! What Construct give you with 16:9 project settings: 480x854 and I upload the image it will be much bigger in a project and then I should manually resize it so it will fit in the 480x854 or 640x360 project.

If I create 1280×720 project, will it be heavier for the device hardware? Making sprites for such size is too much? How to do things right starting a new project?

Guys, please help me to understand those basics, because it's the important base of the project.

Regards,

What sort of game do you want to make?

I'm planning to make infinite side scrolling game(platformer) and to make an app like stopwatch for runners and statistics in there.

bump?

I'd also would like to know what's the optimal screen resolution and ratio for mobile games nowadays.

I have the same question, make a mark here.