Open up a new image with a transparent background 3600 pixels wide and 600 pixels high.
In any color (I used pink f44871), use the text tool to make a dashed line using a hyphen in any font that looks nice, rounded ones will look more like a stitch. Space your hyphens to your taste. If you are wanting to make a crosstitch, then use the letter x. In the example I am using both simultaneously. If you don't like your letter as you are typing it you can change the font size or font without deleting what you have typed. Just keep your Text Editor box open. For this tut, I am using the Orange Fizz font. Note that I have made it so there are about 3 stitches per 500pixels. You don't want to go much smaller than 4 per 500 because they become too small unless tiny is what you want.
[Another way you can do a crosstitch with more added depth use / then copy that layer and then layer>transform>flip layer horizontally. Now you have an x. Don't merge these. After you embellish, you will add drop shadows between that make it look like they are separate.]
When done adding your text, select image>merge visible layers so you are left with a single layer.
I'm going to make a glittered stitch. You can use bumpmapping to make your stitch appear like fabric by bucket filling a new image with your texture and bumpmapping your stitch image. This is where you can experiment. For my glittering, I'm adding noise filter>noise>scatter rgb, then filter>generic>erode followed by filter>light effects>sparkle. My settings are in the pic below.
Add a new layer from the layers dialog box or layer>new layer>transparent. You will want the dialog box open because you will be switching. Make sure you have the new layer selected. It will be highlighted as in the image below.
With black and a circle brush, dot your ends of the stitch. Now go to filter>blur>gaussian blur> (anything between 5 and 25 will do, depending on your taste here, I used 20).
Using the layer dialog box image above, you can see the word opacity, move that slider until dots fade to how you like them. Mine is set at 70. Now hit the arrow down in the layers dialog box to lower your layer. Then select the background layer. From the image select (in 2.2) script fu>shadow>drop shadow. My settings are 3/3/6/60. You can play here or even skip it if you don't want to shadow. And you can tweek your dot opacity and blur to your taste too. Before you close out your image, save it and test it on a scrapbook page. If you like it then proceed to the next options - recoloring. Click on the hue tool in your Gimp Tools window, click on your image and tweek the slider. "Save as" for each color combo you like. If you have two elements on a page like I did then use the my quick crop method - guillotine.
Take your mouse and left click and hold, sliding down until you are betwen your elements, this creates a horizontal guide. Same can be done from the left for a vertical guide. Now go to image>transform>guillotine. This will cut your image apart. Note the auto-renaming. You might want to name and save your parent image before you cut because the offspring will take on the name with some numbers. It makes it easier for saving and renaming later. I just click on the x on the new image and then gimp will ask me if I want to save, then I click Alt-S. Image saves to the same folder the parent image was saved in. I then use my ACDSee program to do a batch rename.