The project has now gained color and value, the most essential part is behind it. Now it's just a matter of finishing and bringing the project to the extent that you want to see it at using different modes and on the Layers panel, you can make interesting effects with the layers on top and above. This can add to your drawing but it they will always it will depend on what you like. So just play around with them. I was also advised to have textures on the drawings and you can download them from the internet and place adjust and transform them the way you like and use the layering process and that's when the layering process comes in. Play around with different adjustments layers under the normal on the layer panel in Photoshop, you will have like multiply or like all of that.
So just play around with it. See what works and what doesn't Don't forget that you can also alter the opacity on the layers itself so that some things may be not as bright and will be see through if you want that effect you will it can add to the picture and it's just very useful thing that everybody seems to forget about but sometimes it does save a drawing Feel free to add details and more shading. If you want to have dramatic quiet and just the feel or the peace this part is up to you to decide when when and what you would want to do with it and how far you want to take it. Remember to not go too far off from the original sketch and the colors because you will look messy I personally when doing things for practice and for my own don't necessarily finish the drawing still it is spotless and look and it looks professional.
Remember this process from start to finish. tremely long and hard and doesn't just take 30 minutes to complete and the quickest you can get to a semi finished result is after a few hours, and that's usually just polishing off some details. Having the right light having everything in place. That's a few it will take a few hours to have a good looking, but don't let that scare you. Because at the end of it, no matter how good the end is, you are doing it for yourself, especially if you're doing it for practice. And especially if you're just starting off doing concept art is just for the fun of it.
You are just doing it for yourself to practice and don't forget to save your project. That's the most essential part.