Great Job :D
I can recommend you 1 or 2 things that'll help you improve
First with the layers: some of the stripes you can notice that is kinda pixelated for this you can add a layer below of the layer containing the stripes and color it with a brush using the backround color (red, blue, pink depending on where you are using it)
Second: Some logos are also pixelated (it also happens with kunos skins e.g: Lotus GTC. so don't need to worry about that but you can improve the looking using imgupscaler.com that website improves pictures quality using AI
Third I learnt this because some mistakes were made when I started making skins: When the skin is done in photoshop or whichever software you use, export the file as png, then with paintshop app (available on rd) apply it over the car, it will look better than exporting directly from photoshop to the game
And remember to enjoy the process :D