Scanlines
Want to achieve that cool effect when you can get diagonal lines on your graphics? Here is a very simple guide on how to achieve that awesome effect on your graphics! And this tutorial is based on Photoshop CS products. =3
Step 1:
First, create a new image by going to File > New. Then make the New Image settings like below:

Step 2:
Next, take the pencil tool and take a 1px brush in any color and make an image like this image below (example below is zoomed):

Step 3:
After that, go to Edit > Define Pattern and name it whatever you want (I named it Scanline Pattern):

Step 4:
Now, we're going to apply the pattern onto a graphic. We're going to use this random banner I made specifically for this purpose (image by Arkeis and texture made by Celestial-Star):

You then have to make a new layer, like this.

Step 5:
You will then have to go to the Paint Bucket, go to the top area, and change the option from Foreground to Pattern. Apply that pattern to that layer, like this:

Step 6:
You're almost done! You will then have to make some modifications to the Blending Mode and opacity of the scanlines, like this:

This is how my banner turned out:

Hope you learned how to use scanlines, and hopefully, you will use it on your next graphics!