Often when we get to advanced levels of drawing techniques in Illustrator (or Photoshop), we tend to forget about the target design and focus more on the complexity of the execution. This also goes for the tutorials, who get more and more difficult, long and exhausting because of that gradient mesh with a gazillion anchor points.
Let's take a look back at our basics, the foundation of what we know today. They are a reliable resource for a quick background or texture, complementing the main element in the design.
The Swatches palette brings a large variety of basic shapes in a pattern and can easily be recolored to fit the design.
The image below is quite flat and boring, it only has a dark, cold color and a light text (the font is "Scriptina" from dafont.com). Nothing special about it so far.

Let's make it more interesting!
STEP 1
Grab the Selection Tool (V), select the background, copy it (CTRL+C) and paste it to front (CTRL+F).

STEP 2
In the Swatches palette (Window - Swatches), click the small
folder-looking icon, go to Patterns - Basic Graphics - Basic
Graphics_Dots, Basic Graphics_Lines and Basic Graphics_Textures.

STEP 3
With the rectangle still selected, click the "Diagonal Lines" pattern.

STEP 4
Go to Object - Expand... Do this twice. The first time, it expands the
pattern and releases it into paths with strokes. The second expand is
for the strokes to convert them to fills.


STEP 5
In the Pathfinder window (Window - Pathfinder), click the "Merge" button, then go to Object - Path - Clean Up. Hit OK.

STEP 6
Grab the Eyedropper Tool (I) and click on the rectangle in the
background to pick the color, then double-click the Fill and make the
color lighter and less saturated. Hit OK.

The trick is to find a contrast between the dark background and the subtle light lines so it doesn't "poke" your eyes when you try to read the text. Given the right contrast, it will also have an emboss effect.

STEP 7
Grab the Selection Tool (V) again, select the text and go to Object
- Expand. Copy it (CTRL+C) and paste it to back (CTRL+B). Hit the
"Down arrow" once to nudge it down, grab the Eyedropper Tool (I) and
click the background again.

STEP 8
Double-click the Fill and select a darker, more saturated color. Hit OK.


STEP 9
Select the text, grab the Eyedropper Tool (I) again and click the small lines or give it a light green color.

You can vary the basic patterns to fit your needs. For the one
below, I used "USGS19 Land Inundation" pattern from Basic
Graphics_Textures.

Rotate the texture after you expand it! In the image below, I used "6
lpi 50%" from Basic Graphic_Lines. It takes a couple of tries before
you get the colors right.

In this design, I used "Crosses" from Basic Graphics_Dots. As you can
see, adding a pink tone changed the design dramatically. Now it
suggests the idea of girl's pyjama or a bedroom.

Need a stylish, Louis Vuitton look? Use the "Petals Three" basic
pattern from Basic Graphics_Nature. Of course, the font I used doesn't
really fit, but I wanted to vary the original design through different
styles.
If you add a leather texture, you're set to create some really cool purses designs with this.


