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When building a PrestaShop theme, you should work with a 980px width and, with, depending on your uses, with:
- One Photoshop folder for all text layers, so that web developers can easily access the design.
- One Photoshop folder per design block (new products, best sales, etc.).
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- Test your theme with all of PrestaShop's options activated, so as to see how the theme reacts.
- Edit a product in order to see how the various options influence your design (promotion, new product, etc. …)... if it does at all.
- Make sure to have a homogeneous style for your shop.
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- Reduce the number of steps (delivery address, payment page).
- Display the errors in a distinct color.
- Payment page:
- If the visitor uses a credit card, warn them that they will be redirected to your bank's secure server. For instance, add a little padlock icon, with an explanation.
- If she chooses to pay by check (or any other offline payment method), clearly mention what to do next: amount, address, etc.
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There are also online tools which can help you optimize your pictures with loss of quality, by performing safe automatic tasks:
- Yahoo! Smush.it is the most well-know: http://www.smushit.com/ysmush.it/
- Kraken is another which at times can give better results, and has Firefox and Chrome extensions: http://kraken.io/
- Image Optimizer enables you to also change the size of the file: http://www.imageoptimizer.net/
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- Pngnq: converts 24-bit PNG files into 6 to 8-bit ones, by only keeping the needed colors.
Download: http://pngnq.sourceforge.net/
Sample command line:pngnq -vf -s1 image.png - OptiPNG: tests several compression methods on a PNG file in order to find the best one.
Download: http://optipng.sourceforge.net/
Sample command line:optipng -o7 image-nq8.png - pngcrush: another PNG optimization tool.
Download: http://pmt.sourceforge.net/pngcrush/
Sample command line:pngcrush image.png -rem alla all -reduce -brute result.png - jpegtran: performs lossless operations on JPeg JPEG images.
Download: http://jpegclub.org/jpegtran/
Sample command line:jpegtran -copy none -optimize -perfect src.jpg dest.jpg
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- Improve your URL's, title and other meta tags: make sure to fill all the textfields in the back-office, both for products and for categories. Use short and concise descriptions, ; fill the title with the most important details , in order to have these details appear in the URL, etc.
- Improve your image display: use proper captions and titles.
- Do not hesitate to use HTML lists when naming the various components/features of a product.
- Use important words multiple times in the product description.
- Optimize page display: make sure they load quickly, either by minimizing image size or by using a better web-host.
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See also PrestaShop free guide on SEO: http://www.prestashop.com/en/white-paper-seo