In the past, I’ve given some tips on working with blueprint editor, but today I want to raise a very important question, that is still asked a lot.
Unreal Engine 4 has plenty of example projects which you can study to improve your skills. What’s even better, you can use any assets provided there for in a commercial product. Simply put, you can take any asset from any example project and put it into your project and then sell your game, and Epic won’t mind.
And though I suggest you try and reverse-engineer Epic’s example projects and then try and make your own asset, sometimes it can be convenient to use what’s already been done (during the early stages of the development, for example). So how do you copy something you like (a material, a texture or even a whole blueprint) into your project?
Let’s take Shooter Game as an example. Open the Learn tab in the Epic Games Launcher and find Shooter Game. Download it and make a new project from it:

Open it in UE and find the asset you’d like to move (it can even be a whole folder). Right click it and find “Show in Explorer” option:

Then just copy whatever you need, and paste it into your project’s Content folder:

BEWARE!
If you copy a whole folder, you should generally be okay. But if you copy a single asset (like a material), it may not work properly in your project, because it has links to the textures, which you did not copy. You’ll have to fix the broken links afterwards.
There’s another way of copying assets from project to project, which is called Asset Migration. You can read detailed instruction in the Unreal Wiki. The difference here from just copying files over is with migrating all of the asset’s dependencies are carried over as well. So if you migrate a material, all of its linked textures will be copied as well.

Cheers, mates.